I'm in a bit of a situation and need some advice.
Bit of background: I'm in a long term relationship, in general we are very happy, we live together and are engaged.
A couple of years after OH and I got together (we were only 16 when we got together) I met a guy (C) through mutual friends. He's a few years older then me. I was about 18 or 19 and was spending most weekends out clubbing with my friends, C and other said mutual friends included. I got on really well with C from the start, we liked the same music and had a lot in common. My OH was a club doorman so he was always working weekends, which is why he wasn't on these nights out. C lived quite close to me, so we used to share cabs or even walk home together after a night out. Some weekends I'd go to his flat and we'd watch films, listen to music and just chill. OH knew all about this, there was never an issue. The issue was with me, where I'd been with OH since I was 16, I was suddenly getting attention from someone else which hadn't happened before, and I liked it. We got on so well, had so much in common and after a while I started to fall for him. I think things had got to a point with OH where, while we were still very much in love, we didn't really do much, we'd stopped going on dates, I was going out with friends because he was working, and I was also at uni so I was busy during the week. We'd lost that spark we had in the honeymoon period and I'd probably say I was bored.
Forward a few months and C admitted to me that he liked me. Well, he admitted this by kissing me when we were walking home one night. And as much as I hated myself for it, I didn't stop him. I liked it. Nothing more happened between us, we became very close to taking it further one night but I couldn't do it. I loved my OH and while I fell for C, my head ruled over my heart and told me that it was probably just because it was new and exciting. We had a long chat one night and agreed that nothing could happen. However, we were such good friends that we decided that we wouldn't stop seeing each other as friends. We'd made a mistake but there was no reason to lose the friendship over it. Things were fine for a few months, we carried on going out with other friends, we had a cheeky glance every now and then knowing what could have been, but that was all. None of the other friends knew anything had happened, and if anything I felt it made our friendship a little bit more special. Now if I was single, I'm almost certain things would have gone further, but it wasn't an option.
In this time that I was friends with him, I was made aware of a girl he worked with that liked him through both him and the other friends. She was constantly texting and phoning him, she didn't like me at all (maybe cos I had a good friendship with him) and he always joked about how she was stalking him and wouldn't leave him alone. We used to text each other just normal friendly texts, like you would with any friend. Fast forward a few months, I hadn't heard from him for a while, so I sent him a text, just asking how he was, jokingly asking if he was avoiding me. I get a reply from this girl (off of his phone), telling me that they're together now, that I need to leave him alone and I'm not to text him again. Needless to say I was a bit taken a back by this, but I decided to leave it - that was obviously why I hadn't heard from him, and I didn't want to cause trouble.
This was about 4 or 5 years ago, and I haven't heard from him since. I cared about him a lot, and yes, I fell for him, but he was also such a good friend that I really didn't want to lose. At the same time, I didn't want to try and contact him as I didn't know how his girlfriend would react. A couple of months ago, I walked past him in town. He looked at me, but didn't acknowledge me, so I didn't say anything. He's recently signed back up to facebook, and I've noticed he's friends with all our other mutual friends on there. I want to send him a message just to say hi and that I hope he is well, but I'm worried his girlfriend might have access to his account and cause trouble. One of our mutual friends moved away a few years ago and came back to visit this weekend. We all went out, but last minute C cancelled. I don't know if its because I was going and his girlfriend wouldnt let him. I've heard from the other guys that she is very controlling and they rarely see him anymore.
So, what do I do? Do I just accept defeat and realise that we're never going to be friends? Or send him a message and see what happens? I honestly don't want anything to happen with him, I just really miss him as a friend. I think it's rare to find someone you have so much in common with, and I would love to be in contact with him again.