My friend commited sexual assault. What do I do?

So I just found out a friend of mine sexually assaulted someone when he was thirteen. He’s in his early twenties now. I’m half a world away and so confused and concerned.

It was someone he was very close with until a few years ago and I never knew why until now.

He was a year or two older at the time, and like I said they no longer are in contact. He’s never assaulted or even considered it in all the time I’ve known him. He is very much against assault and sexual harassment, we’ve had discussions about this kind of stuff.

He just messaged me admitting to it (which his friend had messaged me about a year earlier but he denied it at the time) alluding to killing himself out of guilt. I know he did a terrible thing that will effect this person for their entire life and that can never be taken back, but I’ve known him for almost 8 years now and I care about him so much. I don’t know how to help him or if I should help him. I don’t know what to do and I’m scared he really will kill himself over this.