Why do i have a feeling of self worthless?

My husband I have known each other for 20 years but have only been married for 6 years.. From the beginning I have questioned his devotion and desire to our marriage. For the first few weeks he was the perfect {besides not having a job} husband. Then literally one day he got extremely angry. I attempted to sit him down to talk to him. I my self was at this point once an angry and confused person in this world so I figured that I could p the knowledge to him so he could figure out how to deal with his anger in another way. And at the beginning he would not "pick a fight" in front of my children, not long after, he started to and has continued. I grew up defending my self to everyone. My entire family.. mom, step dad, brothers, sister, aunts, uncles, and even grand parents. So after the initial wore off he started to make comments like he is not kissing any ones a** and if he wants to say something he will and he is a grown man and he does not need any one telling him what to do or how to do it. Ok that made me defensive!! And at this point in our relationship he still did not have a job nor was he putting any effort into finding one so that left doubt in my mind on his desire to help me financially, BUT I ignored it. Until months later I could not bite my tongue any more. He already yelled and screamed in front of my children {that do not belong to him} to me on a daily basis about really personal things so I fired back and the first time I fired back it seemed as though he backed down and respected that I stood up for my self and from the beginning after he would yell and scream and cuss and bash me and my children he would appologize and plead for my forgiveness. But then that quickly diappeared and it did not matter what he said to me and how hurtful it was he would not have a concern but he would hold on to any little thing that I would fire back with. Then I became hurtful and we both would threaten to end the relationship and situations like he would take his ring off and say he can not handle me and my children {2 boys} and he was leaving and I would beg him to stay and even go as far as un packing his stuff for him and things would then be ok for a day or maybe 2 and he would start yelling again and cussing and bashing and I felt us in a viscous{sp?} circle of bitter and anger and hate that I was becoming a different person. He would shove me and body slam me {on the bed or couch and say he did not do it on the floor because he loved me} and even gave me a black eye. Then he became very jealous and insecure with me being alone,,, by now he got a job that he was constantly too sick to work and shifted jobs and was with out alot and it left me feeling that as long as I was ok with him yelling and screaming and not working and just let him do what ever it was he wanted to do, he was ok with that. But if I put my foot down on any situation I was totallly wrong and he did not want to be married to me. So I grew "sick of hearing him say that and became heartless and rude back' and then I would feel guilty and think that every thing was my fault as he said. He would make mean comments and rude remarks to me and my children on a daily basis. So then I figured that he had some kind of anger issues as well as I had and suggested counseling which he denied and said "no one can not tell him something he does not already know". So I burried that idea. And over the next 6 years we became a couple that was quick to defend thier self and bash and yell and I have gone through my jealousy spells. But I feel like it is and has been time to stop fighting and understand each other. I have gone through alot of trama in my life from the time I was 4 and all I have ever wanted was a understanding, loving, caring, respectful family and I feel like I have let myself down and my children and I am left holding the bag on when to throw the towel in.. I am scared that I am over looking something that I may be doing wrong and that I may be to ready to end some thing that is my fault and if so I do not know how to fix it.. There has been alot that has happened that I would need to write a book about for you to know but I hope this quick run down has given you an idea on what is and has been going on. Any suggestions???