Not sure where to start really...
My partner of 4 years has texted another man behind my back. All sexual stuff, not lovey dovey. Let me start from the beginning.
My partner and I have access to each others devices, know all passwords etc. I noticed when he was showing me some texts that he'd sent some texts to his work phone of pictures with him. I questioned why and he said it was a prank at work (they often do this). A day later I was using his work phone to look at the weather, purely as mine was in another room and we'd bene discussing it. While on it he receives a whatsapp from a man I don't recognise, basically saying he wants anal sex. Of course I clicked on it and saw everything. It was a guy he'd met on grindr. It had only started the day before so there wasn't much, but it was very sexual stuff involving anal beads, anal, BDSM, etc etc. From both sides. I immediately confronted him and he went silent and quiet, eventually crying. He told me that since he was 16 he'd occasionally had urges but apart from kissing a boy once when he was 16 (which i didn't know about), he'd never acted on it before. I asked if he'd had one of these urges since being with me and he said he hadn't before this one. He deleted the conversation and blocked the guy, assuring me it was a one off.
This was about a month ago, I feel like I handled it surprisingly well and quite mature. I absolutely love him and we've been through a lot and this is the only reason he's ever given me not to trust him. I didn't see him for a few days then we met up and went through it all, I told him i didn't want to break up, and how I understand that this is a bigger picture than if he was just texting another woman for sex, as its important he comes to term with his sexuality. We spoke about everything from the risk of this happening in 20 years time if he finally decided he was gay, to him having to earn my trust again, and be open about how he was feeling (although we've always had a good communicative relationship).
I don't know what to do. I still love him, I want to be with him, I have put this somewhat behind me. I haven't however told anyone, at all. Am I being a massive idiot for not reacting more, is it a sign that it hasn't torn me apart as it would others? Should i leave him as I know I likely would if he was texting a woman?
I guess I want to know others perspectives before I dive into this again, as I feel too uncomfortable with people close to me knowing, especially if they disagree and I stay with him.
Any advice much appreciated, feeling a bit lost...