Feelings for my ex..?

So, my ex (let's call him Z) and I broke up a year ago, but lately I find myself thinking about him and just seeing random things that remind me of him.
When Z broke up with me (over text BTW), I wasn't sad or anything. I was just like, "Meh. whatever." When he joined my math class in the middle of the year and we started talking as classmates again, I started falling for him again.
Now, we're stuck in quarantine and I haven't seen Z for months, but I've been dreaming and thinking about him for a while now.
Do any of y'alls think it's okay for me to like him again even though he broke up with me with one of the worst ways or should I just move on? ╥﹏╥