If someone lashed out at me over texts I would 100% block them too.
You’re coming across as very needy OP.
You’ve been together a few months.
I would have texted him on Tuesday and said, will you be free on Sunday.
If he wasn’t sure then I would have said that you need to make plans and so you’ll make your own plans and see him on a different day.
I don’t understand why you just sat there waiting on him to see you on your birthday when he never said he would.
Then you get angry with him because you didn’t do anything for it.
The big issue here is the compatibility.
He has his own life. He has a son that he’s close to and doesn’t have a lot of free time.
You are there to slot into his life, he doesn’t see you as more of a priority than his children.
Whilst you seem to have a lot less going on in your life and perhaps don’t have DC or they’ve moved away etc and you have much more free time.
You make him a priority and want to see him before anyone else.
Neither of you are wrong but I just think there is a mismatch with compatibility.
And in all honesty I think you’re very jealous of the son and their close relationship.
I think you want to be the priority but that is never going to happen and I think you need to decide whether you can cope with that long term.