Anyone with step children??

I dont know if I'm in the right forum or not but...
I suffer from anxiety/panic disorder and now depression is difinitely kicking in right about now.
Last night I had a huge blow out with my husband who thinks that my 8year old daughter is sent from hell.  Just to let you know he has two little boys from a past relationship.  They are 6 and 4 years old. I have to admit that my daughter is a pain in the butt, but what kid isnt.  AAALLLLLLLLLLLLL kids bicker and fight but he seems to think that my daughter is the aggressor and that his boys are two perfect angels sent from above.  Everytime they get into it, like all children do, it seems as if he wants me to draw blood from my daughter to teach her to be nice. The poor girl never wins.  If she does something to them, and they retaliate then its "thats what you get". But if they are the ones to start with her, its (what did you do to them for them to do that to you?).  Give me a break!! He'll take the smallest incident and blow it thru the roof.  To tell you the truth I"m almost ready to end it all.  I dont think this will ever change. He is too closed minded to see that kids will be kids and that his kids are far from being perfect. He left last night and has not come home. I know he's with his mom because he called a couple hours ago to ask about OUR baby (we have a 16 month old together. I'm going crazy.  Never have I felt so alone.  You would think getting married and having children loneliness wouldnt be an issue. Go figure.
Advice? Anyone?