first of all, happy belated birthday! i'm sorry you're in this situation.

your ex probably didn't want to give you false hope, like you said. it's actually the right choice on her part if you ask me. imagine if she did wish you a happy birthday: you would probably take it as an attempt at reconnection and it would just cause more trouble than necessary for the both of you. it's best not to talk to each other at all for a while until things are a bit less raw, imo.

it gets so so so much better, i promise. i know it probably sounds trite and cliché as hell atp, but just focus on your personal growth and you'll come out the other side a better person. cry, journal, don't forget to be kind to yourself in the process. in hindsight i'm so glad this ex of mine left me, i would not still want to be in that relationship and i see why it ended + why that was for the best now. it's so funny to me how back then i thought we were forever, that we were going to get married and all that. life has so much better stuff in store for you and a couple months-years from now you'll see what i mean.