I don't know what to do

So my boyfriend and I have been together for 2 and a half years and I love him to death but for a while now I've been waking up to him fingering me, groping me. Sometimes he actually has sex with me when I'm asleep! Well I've said multiple times that I don't like it when he does that and it still continues to happen. And I feel like I can't really do anything about it because I'm asleep and I can't prove he's doing this. I'm really confused on what I should do.