Please help me

I had a falling out with my best friend in the summer. We are still friends but not as close. Her ex-boyfriend is a friend of mine and he told me tonight that he has feelings for me. I don’t have feelings for him, but I feel guilty as fuck that he feels this way and in some ways feel obligated to tell my ex-best friend. But I think she’ll take it the wrong way and get rid of me as a friend completely.