Well if you love her very much and she loves him very much i dont know what you can do. If you tell her she might beleive him and then he would know about it. I would just stay away from there as users said. If she askes you to come over just say your busy - lie, its better than going somewhere your not happy with. If your aunt is there when he is, try and confront her what he is doing maybe?. But im not too sure what you can do. Stay safe.