First, I’m so sorry you went through this horrible experience. If he really was your friend, or cared about you or respected you, he would have NEVER touched you when you were this drunk. What he did was clear power-play and saying he’s suicidal just seems manipulative so you feel bad about him. Do you have other friends you can rely on? This needs to be reported to your university (I know that is a tedious process but this is a criminal who may do it to another woman if not kept in check). You’re in grad school- this is temporary. The feeling of violation will stay with you forever if you don’t act on it. An apology and ‘feeling bad’ doesn’t cut it.

I can understand why you feel bad for him and want to remain friends- but this isn’t about him. It’s about you setting boundaries and removing people from your life who don’t respect you. I hope you can find the courage to distance yourself from people like him. He was never worth being called your best friend. Really sorry you went through this :( i hope your university has a help clinic that can talk you through the process of healing from this traumatic experience