oh Brenda...Your post made me feel so bad. I don't know what to say to help but I'll say this (Because I'm guilty of it too) The grass is ALWAYS GREENER ....
your husband sounds like he has it way better than he wants to admit & by tearing YOU down - it makes him feel better.
one thing I noticed about people who are depressed/and self centered - nothing you do is good enough. NEVER.
The smartest thing I can think of saying is remember hurtful words are just that ....words. Watch his actions....some people just can't ever be a postitive part of a relationship...they let others do the actual work the whole time in their minds .....they're actually critizing us....it's because they KNOW they have lots of room for improvement.
I wonder if you suggest you BOTH go on medication things would turn around ?? He goes back on his Bipolar meds and you get on something for depression ???
I really have NO Business offering advise here

cause I think I'm in the same situation to a degree ....I normally wouldn't say this on a public forum - but you are NOT Alone sweetie. Nothing I do lately is good enough either & my husband is down
all the time now - but unlike you - I'm at the point where things that used to mean alot to me no longer do.....I really miss my old life & this sounds cold but I DO think about leaving....I never would... but man - everything seems upside down you know ??? .... I guess I'm having depression issues for the 1st time in my life but the pills really didn't help me - that doesn't mean it isn't worth a try for you though right ???
and I thank God for the girls everyday - they're my reason to smile these days just like you.....
I'm really sorry and hope things work out for you both. If you ever need to talk you know how to find me - I'm a good listener.