bear with me please its long!
background: 3 dc, eldest has anxiety disorder and is not bio-daughter of dp. relationship 10yrs, generally not too bad. usually great dad.
2 weeks of absolute hell began with him arguing with me infront of the kids after he thought i had spoken to him "sharply", he then try to involve them by asking them if he was in the wrong etc, so i took kids to my parents for the day so he could get out of his mood. next day same thing; no patience with dc, loud and angry infront of them, accusing me of being angry. eldest dd seen bio-dad so dp accused me of "playing happy families", i again went to parents house to remove dc from horrible atmosphere and arguments.
everyday for 2 weeks i have been called, i have been told; this is all me, im bipolar, im exhausted and therfore "having a go", im doing this because of my childhood 
(my parents are not together)
2 days ago dp took dc for bike ride whilst i was busy, came back after 2 hours furious, telling me "shes f*ked in the head!" about eldest dd, because apparently while they were out she had gotten upset after falling off her bike. the same day, after i told him i was actually broken from his 2 week reign of cra, his answer was i like to break things so i know how to put them back together.
fast forward to today and dp has been to docs and has diagnosis of "stress" and is now claiming that he cannot cope with "all the stuff" he has going on in his life (which has not changed in the 10 years we have been together)
I cant get over what he has said especially about dd. aibu if i leave? eventhough he has this diagnosis?
should i wait it out and see what happens? like to see if he is getting treatments? i am really broken here after 2 weeks of being spoken to and treated like this. but does this diagnosis kinda excuse his behaviour?
i just dont know anymore.