It sounds like you rejected your friend’s lesbian interest in you, and now you feel that she’s going after your boyfriend as retribution. 😕 Try not to put too much weight on her and what she does. Instead focus on your relationship with your boyfriend. If things are good between the two of you, nobody will permeate that bond. But if there are problems in your relationship with him, then the relationship is vulnerable. So focus on you and your boyfriend.
As for telling him about this other woman’s attraction towards you, that’s up to you, but you shouldn’t withhold information from him because you’re afraid he’ll pass judgment. If he finds out later that you didn’t tell him something, he may be more upset that you withheld the truth, than if you tell him the truth and he’s unhappy with it.
I hope that helps!