Ex texted me happy birthday after breakup?

my ex broke up with me about five months ago due to some complicated things happening in our relationship. Long story short he didn’t feel loved anymore and our relationship just hit the end of its road. He moved on very quickly and started talking to some girl he met on the Internet. I honestly thought that I would never talk to him again and last week he sent me a text saying happy birthday and he hoped I was doing well. Turns out he’s not talking to this girl anymore. Deep down a part of me is happy that it didn’t work out for him and this girl. And bad wishful thinking that I hope maybe he’s starting to feel guilty about what happened between us. Am I thinking too into it? Why would he text me out of the blue after blocking me and leaving me after almost 5 years of dating? Is it bad that a part of me wants to hear from him again?

Updates
2 mo
so my ex texted me again yesterday.

my friends have reached out to me but i haven’t responded been distant since the breakup happened and i don’t feel ready to talk to anyone about it really.

i guess one of those friends reached out to my ex asking about me. so my ex texted me saying this friend hasn’t heard from me and he asked how i was doing. later on he reached out again saying he hopes im doing well.

do i respond? if i do how would i? why would he be reaching out
Ex texted me happy birthday after breakup?
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