Idk what to do honestly

So me n my ex we broke up in mid October.
I don't think he was serious like I was, because I felt fear of getting judged infront of him and so many more things.

But after a month he calls me and asks how's college going, where I am, how I am and that's it. (I blocked him later because I wanted to maintain no contact forever) After that in mid dec on my b'day he wishes me (on wtsp lol,i forgot to block him on wtsp) On 1st Jan eve, he sent me a big asss para (not that big) of HNY on my mail. I ignored it, didn't reply. Againnn, on 10th Jan he texts me "Hii" on Truecaller. I didn't notice because he is blocked so I didn't get any notification. Again on 11th Jan he calls me. Again I didn't receive any notification since he is blocked.

And and for context, I remember, he didn't bother last year to wish me on new year! We were in relationship for a year and 3 months.

And I realised by thinking on his past actions,he wasn't serious at all before. But now, why? It's already been so hard for me to move on from those things plus my bestfriend of 3 yrs knew that he is gonna breakup with me but she didn't tell me about it. I cut off from her the day itself I found out about it.

Idk what to do mann, whenever he tries to approach, I feel like I should talk but then I remember how the relationship was. I feel so stuck in the loop.

Edit - He was the one who didn't want the relationship so ended it saying "I want to focus on my career" in short.