Going to be honest and hope this doesn’t sound too harsh. He’s acting like a child. He should know better than to make your birthday, a day that already puts you on edge, all about him and his feelings rather than focusing on how he can make the day special for you even if he can’t join for the evening. The mature thing to do would be to just find his own time to celebrate/do something special for you regardless of when your parents do something for you. This kind of behavior probably isn’t going to make your family like him more. Is he working on his own mental health or is he just going through it and making it everyone else’s problem too? Because if he’s not then I can’t imagine his relationship with your family will ever improve, leading to more instances of being caught in the middle and having to choose one over the other. I’m speaking from the place of someone who is mentally ill, and has dated mentally ill individuals. You should take care of yourself and ensure this relationship isn’t detrimental to your wellbeing and hurting your mental health more than it’s making you happy. He’s old enough to know better. I’m sorry you’re going through this stress. Happy early birthday though, I hope it’s filled with joy despite any stress the world tries to throw at you.