Well you two need to communicate. Communication is the key. If you two communicate effectively and are on the same page you will be fine. You cannot let your children control your life. Get back to the basics what made you two fll in love in the first place? Remember this.

I agree with SMof2. The reason you fell in love is not because of his kids, right? I've even been accused of 'breaking up the family' if I say a word against his kids and, because at the time, DH's balls were tucked wayyyyyy up in his innards somewhere, the kids and BM (with her PAS)were helping him to come to that realization, somehow it's all my fault??
It was hell on wheels, let me tell you!
I refused to be bullied into silence, I changed tack a bit. I heard SKids colluding at the top of the stairs and they yelled down at me 'you're not our mom so we don't have to do as you say.' Well, that was my cue to do what I now know to be disengaging. I told them they were absolutely correct, I let them get on with their crap and DH pretty soon saw the bigger picture. I was absolved! LOL I had much more time for my own pursuits, my friends, my whole life! I was very happy, happier still not to have the responsibility for SKids. I told DH that I would help him if he asked me to. It was like I had to say 'Simon says (AKA Dad) you need to do X,Y or Z.
Some communication does have to occurr, it's hard to begin with because they go into knee jerk defense mode but I asked them 'what sort of person does (insert horrible thing) to people?' You do have to oblige them to do any sort of introspection they are able to do.
I wish you luck, all is not lost!

Holy moly. That's a lot of kids. I got confused just reading about them. This may sound cheesy, but it seems like you should have a family meeting and lay down some ground rules for EVERYBODY. YOu and DH should sit down first and figure out what you want, and then talk to the kids together. The rules should apply equally to ALL the children. If the 14 has to do chores, then the other ones do too - even the 20 yr olds. (Or whatever you want. I was just throwing an example out there). Good luck! I hope things work out for you.

I love these comments:

The fact that you haven't all killed each other is amazing.
I had to do it for one little bitch
DH's balls were tucked wayyyyyy up in his innards somewhere

To effectively have a family meeting you will have to give up 60% of what you think is important as a compromise.

If the meeting is successful and he is questioned later he will claim he gave up 60% also.

My point being each has to give up more than their fair share. A professional counselor can be a valuable asset during this process.