How Can My Husband Get His Name Off of the Sister’s House He Co-signed on? She Refuses to Refinance?

refinance

My new husband co-signed for his sister because she had gotten divorced from her husband and would lose her house otherwise. We got married before he chose to tell me him and his sister owned a home! Now I can’t get a house and they aren’t doing anything about it. He has been on her loan for 3 years now, she refuses to refinance, what are my options? Can we sell the house even though her name is also on it? There must be some way out of this!