a great many insightful things have been said here. I want to stress this: what kind of service are you doing to your children, sons at that, letting them witness their mother being abused and treated with disrespect and condescendence? what are they absorbing about the relationships between men and women and the worth of women? how is that influencing their chances for future love, happiness and peace? 
seems to me you are choosing the comfort of the fantasy of what things could/should/“will” be like with your guy over the reality of how they are and have been for a long time. in this respect, tho our relationship and our issues were very dissimilar from yours, I can sympathise and I did the same for a long time, holding on because I didn’t want to let go, because I still loved.
your excuse is that the boys need a father. they have a father. they can still have a father without growing up in an abusive home. what kind of father the father wants to be is and will always be up to HIM.
I would suggest the book “Co-dependent no more” by Melody Beattie. as well as the thread Are you affected by a loved one who is an addict? that’s already been suggested.
my last remark is: that it seems to me you know that you need to change your circumstances and you came here for a nudge. so we are nudging. and affirming that side of you that already knows.
wish you the best, mamma, YOU ARE NOT ALONE.