How do i tell him I don't love him and i want a divorce?

Since i am not in love with my husband of over 18 yrs, i moved out - it was very hard because i felt sorry and i still feel very bad, he is very obsessed with me and refuses to believe that i don't luv him, I have left him many times and end up going back, he has many problems with his daughter who is abusing drugs, we were giving custody of her two children 6yr old boy and 11 yr old girl but because of all my stepdaughter put me thru and still does i am not willing to continue to take care of the kids and continue married with someone i don't luv because of the children, I just found out that they are to TPR of both parents, that means my husband has to raise the kids. Since i have moved out he constantly Comes over and always wants me to go to the house & stay with him, i have stayed at times to avoid problems and help with the kids but he ends up wanting to have sex and i hate when he touches me! And since i had it I don't want to continue to deal with him, he continues to tell me to pray to God and not give up on our marriage B cause we were married by church, how do i tell him its over, I am very afraid of what he will do or how he will react. and of course I feel so bad for him BUT DON"T LUV him! please help with ur advise.