Help Me!

So my best friends boyfriend had a crush on me before he got with her. Me and him argued all the time. Then he decided one nigh to send me a dick pic. And then proceeded to ask for nudes. I told him no. Well I told my bsf what happened. She forgave him but didn’t forgive me. He is now tryna hook up with me. Opinions? What I shouldn’t have done? Should I have told her right when it happened or when I told her (30 min later)?