Search Results: get back at ex after breakup

My ex broke up with me a little over a year ago. It was a very unexpected breakup, and he told me he just didn't love me as more than a friend anymore. My heart was BROKEN and it took a while to get over it even though our relationship was only four months long (he was my first love). We had an argument a few weeks after the breakup and I hated him then, and when he (drunk I'm guessing) texted me this past summer a few months later saying "Hi", I ignored him.

We only ran into each other like 2 or 3 times last semester. Had very surface level conversation, but we were completely civil. Lately I've been seeing him nearly every day because he suddenly goes to the gym at the same time as I do. He seems to go out of his way to talk to me. The first time I saw him, I waved and he waved back. Later that same time he came up to me and started rambling and even said he was sorry about my dog (that we literally put down A YEAR AGO) even though we've had conversations since that happened. Then another time, after he left the workout area to grab his stuff, he came back and flashed his sweatshirt that had my grad school (which I just announced my decision for on instagram) on it to say congratulations. by the way, I unfriended him and unfollowed him on everything after the breakup and he still follows me. Anyway, yet another time he came and asked to use the machine RIGHT next to where I was working out and kept talking to me, saying he'd feel so bad if he hit me with the machine on accident.

His birthday is sometime this month and he invited my closest friends (who one of which he hasn't talked to in over a year and the other he randomly texted her on her bday last month) to his birthday on facebook. Like I said, we aren't fb friends anymore so he couldn't invite me even if he wanted to.

Wtf does all this mean? (fyi I'm not interested- also graduating in a month and he still has a year)