Its very wise to realize when you have had enough, and take the initiative to get help. You are not weak. Sometimes we are stronger than others, that's OK, we're human.
Next time your boss texts you, why don't you text him back and say "Please don't text me anymore, I prefer you to reach me by xxxxx." Just get him to stop. That's setting a boundary, and you are entitled to do that.
Its like the phone, its my phone and when someone is calling, I screen, that I know is going to effect me negatively, I let it go. And if it comes up, I just say, oh, sorry, didn't get to my return calls. And quickly say, how ya doin today? They start blabbing and forget about it.
Have a thought session with yourself and ask yourself exactly what does he do to make you feel like crap. Like a list. Its him, not you. If you can put a stop to anything more, you will be better off for it.
Some people like to walk all over us, but then again, we let them, and they get used to it. Its OK to backtrack and change some things, you have a right to do so, for your sanity.
"Do something everyday to make tomorrow better."
"One good change creates another."