Confused by his behaviour - not sure how to react?

Ok, so I met this guy a few times last year - not very often, maybe once every few months, and even then it was only for maybe 5 minutes or so, so we didn't really know each other very well. We swapped email addressed, mailed back and forward quite a bit, and then eventually phone numbers and just texted (no phone calls initially). We were quite open and frank with each other from the beggining that we were both in relationships and he has a child, so I was never under the illusion that this was anything more than friends talking. I didn't even bat an eye when he saw me nicely dressed one day and said that I turned his head. I just thought he was joking/paying me a complement.

That is until I got a text from him one night when he'd obvioulsy had quite a few drinks. I would have initially described it more as testing the water than flirty, and when he called me later I debated answering, but I did and the conversation was fine, nothing in the least bit suggestive or flirty. So I thought it was my imagination.

The texts then got a little more suggestive and flirty but it was usually when there was alcohol involved. Then there was a phone call, when we both had had quite a lot to drink, and we discussed the relationships we were in (both had rough patches - but I've sorted out the relationships issues with my partner and everything is now fine) and that it was nice to feel wanted by someone else and that it was also nice to feel noticed and attractive by someone else. He said that he'd really like if I came over. I told him that I couldn't/wouldn't as we were both in relationships, and that was fine. He sounded disappointed, but the next day I got a text saying that even if I did come over probably nothing would have happened as he couldn't cheat on his gf, esp as they have a child. So I told him that nothing would/could happen and that it would be better that we ignored what had happened, which he agreed to.

I met him properly a while after that, and things seemed fine. We spent an hour or two chatting among friends and there was nothing suggestive even intimated, though there was obviously going to be a little bit of apprehension there given what had happened. But coffee passed off fine and I thought everything was fine until I got a text from him asking if my friends had asked about him, and what kind of questions they asked. I gave him the standard spiel and he asked if they thought he was good looking. I just laughed at it and passed it off as a joke as I did when asked if I liked spending time with him. He then said that he liked the fact that I'd taken off my cardigan and he'd have liked it even better if he could have took off my top. I didn't reply, but I got a text within 30 seconds of the first one saying he was only joking. When I replied I made some joke of it, but I haven't heard from him since.

I haven't texted/called him since, though I did email him about something that I was to get back to him about, but I haven't heard a word from him since. IT could be that his gf saw some of the texts/emails that were sent (by both of us) and gave him an ultimatum - which is completely understandable. Or it could be that he mentioned it to mates who told him to cop on. Or he could just be feeling so guilty that he pushed things too far and because I didn't reciprocate his advances he's embarassed/annoyed and feels the easiest way of dealing with it is to ignore me and cut me off.

Even though there are lots of reasons I'm confused as to why he suddenly cut all contact as he did and I'm probably a a bit hurt that he just stopped all of a sudden without an explanation. It's probably compounded given that he said he considered me a friend and someone he could talk to about anything... Obviously I'd like to know one way or another why he changed so suddenly, and would like to ask him, but not sure if I should push it?

Also, when I see him again (mutual friends, so it's inevitable) should I just ignore him? Or say hello and leave it at that? Or talk to him normally as if nothing happend? I'm completely confused so Any advice would be appreciated.