Can rent paid in advance be refunded?

[Harvey Williams]

About two months ago I moved in with my boyfriend and signed a six month lease with him. We paid the entire six months upfront. We broke up and he moved out, and now he's saying he's going to try to get out of the lease. I'm afraid that he will convince the property management company to take him off the lease, refund him the money he paid upfront, and make me responsible for his half of the rent for the next four months. I can't pay his half of the rent and I would rather have him stay on the lease than have to pay that money. Is it likely that he will be able to get off the lease and make me responsible for everything without my consent?