Emotionally abusive ex acts like nothing ever happen and keeps hanging around?

[Alex]

So my ex works with my mom to water that down. I came into work to help her with a charity breakfast and my ex was coming in for his shift too. I was expecting him to not make eye contact with me and totally avoid me since we had a bad break up and the last thing i said to him about a week ago was I am done being treated like crap ect. He is emotionally abusive and there is a high chance of him having bipolar depression. Anyways, he comes in all smiles "hey how are you" gives me a hug, totally ketches me off guard. As the time goes on he does a whole bunch of stuff he never does when he's at work like like taking a break from his task that he is not suppose to nor does anyways as well as volunteering for tasks he never does and just comes over and hangs around me not taking to me just being around me. I am the one who made small talk but it is so awkward you can just tell. Now I just don't get it why are he was around me like we don't talk but i have a gut feeling he's on my social media sites just lurking and stuff just i don't understand.
What are ur thoughts
thanks
-Alex <3