My wife (31F) “broke up” with me (34M) and still expects me to help pay her share of the rent

My wife and I both make pretty good money, and we just signed a 12-month lease for an admittedly overpriced apartment in NYC, $6000/mo for a 1-bedroom. We've been together 7.5 years, married for 2.

She's been stressed about saving money, so I offered to pay $4500 and she could pay only $1500. We're both named on the lease.

She "broke up" with me a month after signing, refuses to see a therapist to attempt to repair, and wants to move to Europe.

We have a prenup which considers all of our personal finances separate, but says we'll split joint assets & debts 50/50 (basically furniture, and our joint credit card).

Since we're "broken up", I consider my offer to help pay her rent cancelled, and we should each pay $3k/mo until we can escape the lease.

She thinks the offer still stands she she only has to pay $1500/mo, leaving me paying $4500 for an apartment I don't even want anymore (she actually picked the place, it wasn't my first choice). She also asked if she could leave immediately and pay $0, since I'll have the apartment to myself.

I've reached out to the landlord, and he said we're responsible for the full amount until the end of the lease, no exception. (He suggested we stay together instead!)

TL;DR: I'm trying my best to find a subletter ASAP, but no luck so far. Do I have to pay 3/4 of rent? Should I get a lawyer even though this is our only financial conflict?