Am I bad person?!

I’m kinda panicking. My best friends ex boyfriend likes me, and I think I’m starting to catch feelings. I didn’t know either of them when they were dating because I had gotten close with them this year, and they broke up 6 months ago and they were dating for 2 months. She knows that he likes me because he had told a friend of mine and it spread to me and all of my other friends, and I told her that I would never like him unless I got the OK from her. She said that she personally thinks he’s a dick but she isn’t going to stop me if I want to date him. And even though she said that I still feel guilty that I have feelings for my best friend ex. What should I do?