How can he show me he believes me?

So, this is a crazy story. I will be short.

When I was 15, I was molested by my husbands best friend. (Idk if it’s considered molestation.. he was trying to force it but it didn’t happen)

Anyways, I didn’t tell him until 2 years later. He didn’t believe me. Then he came back and said he did, and he was sorry. We got married shortly after. For the next year, I thought he believed me until I heard him on the phone with his mom and he told her. She LAUGHED and said it was a lie, he said “yeah I know” I never told him I heard that. Another year past and we got into a fight and he goes over to this guys house for 6 fucking hours and hangs out. When he came back, we talked and he said he confronted him about it and could tell he was lying. He said he was in denial for so long because that’s his best friend and he just needed to see for himself. We went to marriage counseling and he apologized and all that.

A few years later passed. We just had our third child and a few weeks ago we ran into this guys brother who told my husband to stop by and hang out with all of them sometime. We talked and my husband was sad. He said he won’t talk to him because of what happened but he’s sad because that used to be his family, like his brother. He then told me that night when he confronted him he couldn’t tell he was lying..

Now he keeps saying he could and he doesn’t remember saying that. He says he loves me and will never talk to him again, will never hurt me again, etc. but yet he keeps saying that he never said that.. but he did!

The reason I’m still with him is because we were so young when all this happened. He was only 18 when he found out the guy he’s known since he was a kid did this. Of course he didn’t believe me. He says he will do anything i need for him to show me that he believes me. But is there really anything he can do? I keep thinking about when he said he couldn’t tell he was lying and he swears he didn’t say it. He just says “I’m telling you now. I believe you” he told me he would confront him if he has to (obviously I don’t want that) but he would have to get drunk first because he’s scared.

Besides this problem, he’s an amazing husband and father. This is literally the only problem we have. I just don’t know what to do. Part of he thinks he’s just a piece of shit who doesn’t deserve me and the other part realizes that he was just a teenager and didn’t know how to handle the situation. I am seeing a therapist now and we have started talking about ways to make our marriage work but I need some advice from strangers. I’m not in the wrong right? What can o have him do to prove himself? Or will he just do whatever I say and not actually mean it? And it’s weird that he said he would have to be drunk first, right?

He won’t get arrested even if I reported it because he was only 17. I have absolutely no proof and my husband apparently told them all I was lying so he has ALOT of people to back him up. Me on the other hand.. have no one. This was years ago.

I know I should just move on but doesn’t it matter if he believes me or not? Would you want to be married to someone who doesn’t believe you were sexually assaulted?