My boyfriend (20M) continues to be around someone who made me (20F) feel uncomfortable and unsafe

So my boyfriend and I have been together for nearly 2 years. This situation is quite simple, but is confusing me a lot. My boyfriend has a best friend, call him J. We went to a sort of get together/ party thing a few months back at J?s house. His father was there, and was drinking a fair bit. Around midnight, J?s father starting to get really close to me and hug me from behind and was trying to feel up other girls even when asked to stop. Mind you he is like 50 something.
I informed my boyfriend of this the next day, and he seemed to be taken aback and angry. He said it was disgusting behaviour. However he has continued to hang around J and his father multiple times since then? He?s even at one of their get together right now, and he was invited by J?s father.
What should I do?
TL:DR - boyfriend keeps hanging around someone who was trying to feel up myself and others when told to stop.


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