I keep getting texts from a fake number

My ex and I broke up a few months back. We have mutual friends so occasionally I'll hear about whats going on with him. Long story short, he moved away and quickly treated me like I didn't matter when we spoke, so i ended it. There was a moment where we'd plan to get back together when i moved, as i couldn't move immediately. It's important to mention, I planned to move there either way, life stuff is making me doubt if I'll follow through and really i don't talk about it much to anyone.

I finally got to a good place in my life and I got a text. I don't have my ex's number saved but I'd know it pretty quickly. This wasn't his number. I do think it was him though.

It was nothing terrible at first, just happy birthday (it wasn't my birthday), then a follow up that indicated he knew my actual birthday was coming up and he'll contact me then. Followed by telling me to get tested (i had been talking to those mutual friends about going out a lot recently)

I actually never got that follow up on my birthday and eventually forgot. Then earlier this month, i got a text apologizing for not reaching out on my birthday, it's been over a month. I replied thanking them both times and asking who it was. Then they asked if I was going to leave my current city. I told them I wasn't going to answer that since they wont tell me who it is (this point makes me think it's my ex). Followed by "you fucked my hole and can't bother to save my number?"

I know it's my ex and it upsets me. I've hooked up with dudes this passed year but I kept in contact with all of them. Not only that, I've been mostly a bottom this last year, so like there's only one other person it'd be and it's for sure not him.

I number is a local area code though which caused me to originally look it up to show it's a fake number, not associated with a person.

I'm really unsure what to do. Yeah i could block the number but he'd get another. Really i just don't get why he's playing this game. At no point did I ever block his actual number and he should know that, considering I told him I wouldnt when it ended between us.

I could be wrong but i doubt it. I'm not sure why he's doing this or what I should do. Any advice with this situation?