I'm not a good mother

I think I'm pregnant and I dont want to be. I have some signs of early pregnancy. I have been pregnant 6 times in the last 10 years, all times were planned however only 3 of them resulted in a child. I've since split up with this man. He was abusive towards me and my daughter. He has washed his hands of our daughter and refuses to see her but has my 2 sons and refuses to let me see them, we are going through court atm. Its been a year since I left and I am with a new man who treats my daughter and I like we deserve to be treated. He is fantastic and we are madly in love and have been living together for 3 months now. I've no doubt that I have found the one. He has 2 children so together we have 5. I'm terribly upset about this pregnancy because I feel as though I should be happy, my partner is, we are in love and extremely happy etc. But if I'm honest I feel as though I've failed my children and I have no right bringing another into this world. My daughter was emotionally abused by her father, I knew yet I didn't have the strength to stop it. I let him do it. I know I left in the end. But I let him do it for 9 years first. I feel guilty that my sons are there with him now and not with me. I failed them too. He hasn't let me see them in 3 months. Sure I'm fighting in court but they don't understand that. They will think I've abandonded them and am playing happy families with someone else and his kids. I try, but I don't believe im a good mother and I don't believe that I'm worthy of having anymore children to screw up. Its too early in our relationship to start with. He was shocked initially but is excited now. I don't want to admit to him how I feel because these are my deepest darkest thoughts. And please, before anyone says anything this baby was conceived with one missed pill AND a condom. Its not like we have been having unprotected sex.