Text my ex

So my ex and I dated for a year in a half till he decided he couldn’t do it anymore. He still says he loves me and that me and him will always be friends and hang out. He also told me, that me and him would get back right once he gets himself together because he wants to be the man I can be proud of. Even though I am already proud of the person he is now, I still want the very best for him.

His birthday is coming up in a week and I want to text him happy Birthday but I’m not sure if I should or even what to say.

Am I out of my place if I do it but more importantly what do I say to him?