So I am in great need of some advice. This might be a little long so my apologies.

I am 31 and my husband is 40. He has 3 kids from a previous marriage (20, 19 & 17). We have a daughter together who is 6.
I raised the 19 year old and the 17 year old for the past 8 years.

The 20 year old and I never had a good relationship. She has done it all from calling me name to telling me awful things. I stop seeing her after I was pregnant and she kept threatening to push me down the stairs and hoped I would lose the baby.
Since then I have not talked or seen her. My husband talks to her every now and then.

The 19 year old and I had a great relationship till she was a senior in high school, then I dont know what happen. She graduated but decided to lie about going to college (Saying she applied, and never did) she got also quite rebellious. She lived with us under the condition that she had a job and applied for college the follow year (This session in September). Well she got a job and would only work 8 hours a week no more. and again did not apply to any colleges. By March life was miserable in our home. My husband finally told her she had to leave. He made her go live with her mother, whom I was hoping would be just for a bit while maybe she would realize that she needs to be in college. Her mother is a poor excuse of one. She is on her 3rd marriage. When my step daughter moved out their mother was living with a boyfriend. Well it wasnt a wake up call for her it was more of a party time, since her mother was never around and did not care anyway my step daughter as now started drinking, smoking, doing drugs and having sex, all things she was very much against till recently. (Frankly the sex I dont care, but when its multiple partners in the matter of months ... its just gross).
She has sent me emails tells me to drop dead that I was never a mother to her and that I am nothing.
This broke my heart, I love her like a daughter ... I am not sure I still do, that just ... in my 31 years alive I have never been treated so horribly by anyone till I meet these kids!!

Finally my step son ... he does what he pleases. He goes through my things, takes me things. Doesnt care. My husband pretty much lets him because if he tries to talk to him my step son just ignores him.

Its very hard on me. I am just at a lost.

I found out that my husband secretly talks to his daughters (which I dont really care I guess) but he has to do it behind my back! He says to not get me upset. But then says he is going to take my daughter to see her sisters. When I dont want her to see them. Why? Because why should she be around 2 people that hate me?
He says they dont hate me, they think I hate them.

And they all know I dont. I have morales and some of the things they do I dont agree with. The 20 year old ... she was in college, she had 1 year left decided to get pregnant and drop out ... how crazy is that? So she rather go on wellfare and work at a gas station then finish her final year?
The 19 year old ... She has been a drama queen since I meet her. She has made up everything, from health problems to other things just for attention. (Examples, she went to school one day she was 14 I think, and her cousin just had a baby and she showed pictures around the school saying it was her kid, another example? She wrote all over her self "Die" in pen and told her brother and some family she heard voices in her head and they told her to kill herself, we got help right away, 3 months after of seeing therapist and psychologist which all said she was fine, she admitted it was a lie .. I can go on and on). I dont want her in my life. At all.
She just is drama. She will cause problems just to get the attention and I had it. After she said what she did to me and I just cried for a week, took me a week to crawl out of bed and face the damn world she wants me to welcome her back, and I cant... I just cant!!!

My husband is mad and says I am wrong.
I finally told my husband today I dont know if I want to be married to him anymore, not if he will take his kids side when he knows what I believe in and that after his kids are doing what they do I should just roll over and accept it? I cant ...

Not sure how much sense this post make I am just so upset. All these kids seem to hate me but I really have not done anything. At this point I just want to walk away, which isnt easy since I have no family to turn too myself so I just dont know what to do anymore Am I wrong? Should I just let these kids walk all over me forever just to stay with a man ... that I cant say if I truly love anymore if he cant even see my side of this?