Breaking a Lease: Removal from Lease

My question involves landlord-tenant law in the State of: Wisconsin

I am wondering what my options are. My girlfriend and i are in the middle of a breakup. We recently signed a new lease and it isn't working out. We are both on the lease. She plans to stay on for the duration of the lease. Lease says we are joint and severally liable for the rent. So here is where my confusion is.

The lease states that...

There is a lease assignment fee of 1 months rent.

The resident handbook we received along with the lease prior to signing the lease states...

The penalty for breaking the lease is 2 months rent and we are required to move out by noon on the last day of the month paid.
Any rewriting of the lease needs to be agreed upon by both tenants and the fee is $250.

At this point I just want to be out and understand there will likely be a fee. My question is, which fee would apply?

I paid half the security deposit, which I'm sure I'll never see and I'll chalk that up to a lesson learned.

Thanks for your help, hopefully this all makes sense.

Breaking a Lease: Removal from Lease