My ex has "moved on" but why is it that he constantly staress and me?

Me and my ex broke up 4 months ago, haven't talked or seen each other for straight 3 months. During that time, neither of us had dated anyone else. Although as school started a month ago, we saw each other again. I could feel it was hard and really awkward for both of us still to see each other again. But as a little more time passed, I found it actually a lot easier that I saw him around again. We talked here and there very casually when our mutual friends were around. Neither of us could look each other in the eyes.. But because of those little things, the remaining feelings I had for him started disappearing a lot faster, just because I knew it didn't have to be awkward anymore and we could still be friends.

A week ago, I guess him and this girl started "dating". So they aren't official.. yet. I never imagined him being with another girl, and I was pretty sure I would be devastated if he ever did. Although the jealously feeling hit for about a good 4 hours and I didn't even care. Because to be honest, that girl is nothing to be jealous of.

What bugs me now, is I still catch him staring at me every time I'm around. And there's a couple times where he will try to make sure I'm looking over there when the girl is around just to see if I see. Oh trust me I do.. I don't think he is just trying to get me jealous, because he obviously have been going on social network and rubbing it in "how happy he is". If he still had feelings for me, he should know doing things like this doesn't fix anything! Only makes it worse. Does this mean anything or am I just over thinking this way to much?!

This was a 7 month relationship.. and we were both each others first real relationship.

He broke up with me to just get a break from all our fights and I guess in the end I did loose his trust in me, didn't cheat, but might as well of. We both hurt each other bad, and the break up overall, was just not good.

Hmm...he might just be wanting to make you jealous because maybe he is still hurt and wants to get at you. But if he does have some feelings left for you, he will come to you himself.