Hi,
I will try to keep this story as short as possible, but it's very long..
When I was 19 (I am now 27), I had my first "big love" (let's call him 'M'). I had dated other guys before this, but this was the most emotionally intense relationship for me. He is three years older than me. We dated for about 1.5 years, and the relationship ended mainly because we were in different places in life. He was finished university and didn't know where/what to do, I was still in university and pretty immature. We always had this crazy, insane chemistry, though. After we broke up, we tried to be friends b/c we valued each other, but always ended up sleeping together, and then sort of dating again. This went on for probably another 6 months, then I finally ended it altogether.
2-3 years passed, during which I was in a very serious relationship (we were engaged), but things fell through. I randomly bumped into M's sister, and this of course got me thinking about him. I decided to look him up on facebook, just to say hi, and see how he was doing. He wrote back, and was very happy to hear from me. We chatted for a while via fb, and it was obvious he had a serious girlfriend (lots of pictures going back a few years), but he would never talk about her, even if I asked. Eventually, he asked if I wanted to meet up for a coffee. We met, and talked, and he told me about his gf and all the problems they were having. I offered him advice about my long term relationship that had ended.

Meanwhile, one of his friends started dating one of my friends, so we ended up spending more time together socially. One night, after a few drinks, we ended up making out. He asked to come home with me, and I told him no. He had a gf (I was single), and I wasn't about to be his drunken afterthought. The next week, the same thing happened. The next week, he asked me to go for coffee, and tried again. The 4th time, I really couldn't say no. I wanted to sleep with him, and he had tried 4 times at this point, 2 of which he was completely sober. So we kept seeing each other, and sleeping together, for about 2 months, behind his gf's back. The insane chemistry was still there, and he told me he still had feelings for me.

Again, I started to get frustrated with him, and told him we needed to stop. He was unhappy in his relationship, and I told him to either tell his gf or break up with her. He wouldn't do either, so I called him a coward and walked away. A few months later, he broke up with her, and I was in another relationship, although I often thought about M and wanting to be with him. I often have dreams about him.
He took a job in Dubai, and moved there about a year ago. We have kept in touch. A few months ago, when I was newly single again, I was chatting with M. He told me that he couldn't stop thinking about me, and I told him the same thing. We have chatted very regularly since then. He told me he was coming back home to visit in August, and asked if he could see me, so I agreed.

M arrived last Friday night, and called me immediately, saying he needed to see me ASAP. We met up on Saturday with a bunch of friends, had a great time, and he came home with me. We had an amazing night...very hot but also close and intimate. The intense chemistry is still there.. We met again Tuesday night, and talked for about 3 hours after we had sex. Then we went for lunch Wednesday and talked for about 4 hours. He has been very sweet this week, and telling me he misses me, and wanted to cuddle at night, and brought me a small gift from Dubai. He has so far spent about 30 hours of his week long visit with me. He has asked me everything about my life, and everyone in it, and told me everything about his. I definitely still have feelings for him, and have dropped a few hints this week. He is leaving tomorrow for another year abroad.

Sorry this is so long. I guess my questions are:
1. What the hell is going on? We have had this ongoing "thing" for 8 years now.
2. Was I a convenient booty call for his trip home?
3. What should I do about this? Should I tell him how I feel?

Thanks!!