回複：我該賠 這筆錢 嗎?

I check the law carefully, you and your friend most likely will not be trespassor. But you probably violated the lease or reasonable rules established by your landlord and her boyfriend. Therefore, you will be responsible for breach of contract, namely the lease or the oral agreement between you and your landlord. If the boyfriend does sue you, you will have to pay the damage if he can prove it. But your friend should reinburse you for some of the amount you pay, after all, it is his fault too.

At last, do not hide or try to avoid it. Face the problem, you will be fine.