My wife (37F) and I (38M) want to adopt our teenage foster daughter but FIL (64M) is furious about it

My wife and I have two biological teenage sons, one older and one younger than our foster daughter. We have been fostering kids for many years but the goal has always been to reunify the kids with their parents which has happened successfully each time until now. Two years ago we took in our foster daughter, now mid teens. She had been through a LOT and was labeled as a "troubled kid" and not adoptable. I won't go into details, but the issue in this matter is that there are images of her going around amongst a certain community from before we took her in. We were informed by authorities about all of this before so it's not like this came as a surprise after we got to know her.

I'm not going to lie, it has not been easy. Our families have seen us struggle but almost everyone has been super supportive. The first 5-6 months were the hardest. She didn't trust us, and she was angry at the world – rightfully so. Then one random night I got up in the middle of the night and unintentionally ended up scaring her shitless, and she had a full-blown panic attack. She was ok after a little while but it was like something clicked for her that night. It was like she realized that we were on her side, and we watched her change from this angry and sad little girl to the ambitious young teenager we know today. It started with her telling us thank you for everything we did, small things like driving her to practice. And she said it with a smile on her face. It was so amazing to see her feeling better and not so lonely anymore. From there everything changed. She made new friends and got a lot closer to my sons, especially the older one. Her grades went from failing multiple classes to getting straight A's. Not because we were nagging her, but because she wanted to. Each member of our household has developed a good and strong relationship with her and the love we have for this girl cannot be put into words. We've reached that cosmic connection. She still struggles with a few things, which is totally fair after all she's been through, but she is working on it, and we are supporting her in every way we can. Overall she's doing amazing, she's so strong and I'm very proud of her.

We made the decision to fight the system to change their verdict from not adoptable to available for conditional adoption, because we want to commit to her for life. We want to adopt her. Last month we got the call that they changed their verdict, and we sent in our papers that were already ready and things are looking very promising.

The thing is we haven't told her yet. She knows that she is now adoptable, but we haven't asked her if she wants us to officially adopt her yet. My wife and I have talked to our sons about it, and they are fully on board. We talked to my parents, our brothers and sisters and their spouses. All of them have a good relationship with our daughter, and every single one of them is so supportive of our decision and willing to fully welcome our daughter into our family.

Then there is wifes parents… MIL hasn't been awful I guess, but maybe it's because I'm comparing what she said to what FIL said. We told them about our plan and asked them about their opinion. MIL asked if we were sure as our daughter doesn't quite "fit in". My wife and I didn't understand at all since our daughter has a very similar personality as we and our sons do. But it turns out she's concerned about the visual side of it as she's clearly not our biological child and people will start asking questions. The thing is, my wife, myself and our sons are very tall. Our daughter is not. She is tiny compared to us and has a similar eye color but not the exact same. All 5 of us have the same skin tone and colored and textured hair. Not that I think this matters AT ALL(!!!) but the stupidity of it is unreal! Apart from height she could pass as our biological daughter, so I'm starting to think this is a lame excuse for something else. I told her that people would ask questions no matter what, because even if our daughter was the spitting image of my wife, it's not like she suddenly gave birth to a teenager two years ago. And the answer to any question is very simple. "She's adopted." Tadaa! It's not like it could ever become a secret now, so I don't get it. MIL didn't say much after that but it was very clear she was not on board. FIL hadn't said anything, but he didn't seem excited at all. I asked for his opinion, and he just stared at us for a minute, and then he said "Don't do this to yourself and our family." It's safe to say I was confused but I had no idea what to say. After a few more seconds he went off! He started talking about their family name, and he didn't want that ruined by a little wh**e and what would people think if they saw these images floating around on the internet.

I was stunned! My wife couldn't find any words either and started crying before she just left. I didn't say a word while FIL finished ranting but 1000 thoughts went through my head. Eventually he stopped talking and I still had trouble finding any words to say. I just told him "you are sick!" and I left too.

My wife is destroyed after hearing what her father thinks about our daughter. We have no idea how they know about these images as we haven't told anyone about it. I'm 100% certain my wife didn't tell them as their relationship is not that great. My wife is closer to my mother than her own so that wouldn't make sense.

We have tried to hide this from the kids since this happened, but my older son sensed something was very wrong and asked about it. I told him our conversation with ILss about adopting our daughter didn't go very well, and they weren't supportive. He wanted to know why. I told him I couldn't tell him, but that it was serious and promised to talk to him about it in a few years when he's an adult. And I assured him that our daughter didn't do anything wrong, our plans haven't changed and that it's FIL who is being unreasonable. My son told me that our daughter told him a few months ago that she didn't think ILs liked her very much, especially FIL.

This happened two days ago, and we haven't spoken to them since. I'm not sure I even want to try tbh. For me this is going no contact worthy. I want nothing to do with them. My wife is in pieces and has mentioned that she doesn't want them in her life after this. This has tainted our adoption experience for sure.

I'm afraid though that if we piss FIL off even more that he will start talking to our family about these images. I do realize that he will look like a pig in everyones eyes, but I would like to spare our daughter from everyone knowing about what's out there.

I usually talk to my mother about heavy stuff in life, but I cannot talk to her about this without feeling like I'm exposing my daughter by telling my mother more than I want to for my daughters sake.

Internet strangers… I have no idea what to do from here. How do I go about the situation with FIL without creating more mess than absolutely nessesary for my daughter?

Edit to add: Just to be very clear! There's no doubt in our minds that we still want to ask for our daughters permission to adopt her! Our relationship with our daughter will not change no matter what FIL does or does not do. I realized from the first couple of comments that it became unclear after the FIL incident. Sorry about that.

Edit to add 4h later: I'm glad to see I'm not the only one possibly/hopefully reading too much into this. I think you have verified I'm not crazy. Wife and I had a brief talk after I posted and have decided to talk to her brothers and sister first about FILs comments. It will be a very hot conversation but it needs to happen. Before I could get to it, my wife told me she wants to report the situation with her father knowing about the images of our daughter. Right now we don't know what that looks like but it has simply not been possible for him to gain this knowledge legally. There is a culprit for sure, but we will leave that to the authorities for now. Thank you for giving me a reality check! And thank you for your encouragement, we need it right now.