Wtf does he do this?

Those of you who read my last thread know what's going on... For those of you who don't, please read it (it's a bit long, but puts things into perspective).

Last night was a mutual friends birthday. We are both very close to him, so I knew we were both going to hang out. On Thursday, we celebrated this friends birthday early, so myself and a few friends went out with him to celebrate it. My ex showed up with his brother and his brother's girlfriend (these two have something against me). He completely ignored me. I was confused and hurt by this, because earlier that day, we had met up for some Kiva Juice and had a really nice conversation. Anyway, so at the bar he was ignoring me. I decided to be the bigger person, and approached him. I hugged and said hello then sat down next to him in the booth. He slid practically to the middle of it and just got quiet. So I left outside to have a cig to calm down with my friend. When I went back in, he was gone. Didn't say goodbye to me on the way out, he must've snuck past me.

So last night, we are all hanging out at my house watching the boxing matches that were on last night. He's there, barely says hello again. After everyone leaves the room, and it's just he and I, he asks how I've been, how our son was this weekend, stuff of that nature. But as soon as everyone came back in, he stopped talking to me.

After the fights, we go out. This was awkward. I thought everyone was going. Well, it turned out just to be me, my roommate (a guy), the birthday boy and my ex. I don't mean to sound arrogant or anything, but as soon as we hit the first bar, I got a lot of attention. I ignored it. I think my ex noticed this. My roomie and I discussed the situation on the drive over there, and he told me he was going to be honest, and that my ex and my friend were more than likely going out to pick up on girls. I had already figured this out, once I found out it was just going to be the two of them. So anyway, here we are at the bar, all sitting down. drinking. talking. awkward. Then we move to the next bar. Again, right off the bat, some guy approached me. I stayed bullshitting with him for a moment, and looked to my friend to get the guy away from me. Eventually, my ex litterally stepped in between myself and this guy and stayed talking to him. After this, my ex starts making moves on me. I was being friendly, but knowing I was his fall back hurt. So I wasn't too talkative. The entire night, he continued doing this. Just being flirty. I think I hurt his ego because I wasn't giving into it. Why should I? I was his fall back. The bartender started hitting on me. I actually talked to him a bit, I wasn't being super flirty, but I have to admit, It felt great knowing that this was going on. I hoped it would get my ex's attention, maybe open his eyes as to what a catch I am. He just continued to make his move. Eventually, one of his friends showed up and I overheard his friend telling him "She just loves that you're here right now". He wasn't wrong, but it's not like I was rubbing it in my ex's face or anything. It just happened. So at the end of the night, we're getting ready to leave. He gave me a cold "goodbye" then walked away. As soon as my roomie and I got to my car, I cried like an idiot. We got home and I was crying. Then my ex called. My other roommate took my phone from me and hit ignore. They said I was in no condition to talk to him, being that I was so heartbroken. He called 6 times and texted 5 times. As badly as I wanted to talk to him, I knew my roommates were right. My roommates, are also very good friends with him. We come from the same group of very close friends, so it's hard and nearly impossible to get away without having to see eachoter. Our son also makes in concrete, we are going to have to see eachother. Today, I talked to his mom, she and I are very close. She told me he talked to her about last night and said he noticed I was distant from him. He said things felt like a game, and I agreed. I'm tired of the game. I don't want to play games. These chasing games are so stupid. I hate them. So I told him I wanted to talk to him today, and he said he'd meet up with me when he got out of work. Well, now he's just blowing me off. So can a man explain to me what the deal is with his behavior? I'm distant because for three months, after we separated, he would lead me on and then break my heart almost every other day. Said he didn't want to talk to me. He actually aknowledged that at one point last night at the bar when we were alone "So how have you been? We haven't really talked in like 2 weeks". So wtf is he doing this? Why did he chase after me last night, then call a ton of times. But will do something like this?