Should i have an abortion?

I am a single mom of 2 kids there dad and we split up and he is in the military so he is gone more then he see them. I was dating what was my bf for about a year and a half after a year we started talking about trying to have a child because he has no kids yet. Well we have been trying for the last 6 months and had no luck. 3 weeks ago his exwife came back into the picture (this women left him for another man who she went on to get engaged to drained his bank account, stole from him, lied to him) needless to say she came back crying how she was sorry she regreted what she did she wanted him back all that, so he told me he loved me but he loved her more he was married to at one time and he felt that they could work it out. I found out yesterday i was pregant. I called him right away to tell him and it was like he was more concerned with how she was gonna take it and if it was gonna affect them getting back together which clearly made me upset because this shouldnt concern her. Well we started talking about out options and what we were gonna do and we couldnt agree on anything from the start he was like i want joint custody and this baby on all holidays and it turned into one huge fight. And the women he is gonna be with already has 3 kids which she has none of them in her custody cps removed them from her care and pretty much said she is unfit. I told him when this child is born i do not want her around my child seeing how she couldnt care for her own and everytime she looks at that child she will see a part of me and i am honestly afraid she woulf try to hurt my child, but he thinks if she is gonna be in his life she should be in this childs. She sits there and bashes me to him and already is telling him that he isnt gonna take all their money and suport this child and its just gotten so outta hand. I really thought him and i were gonna be together i never thought he would take her back he had stated to me so many times how much he hated her and would never forgive her. I love this child thats inside of me already but i am already a single mom of 2 kids struggling to make ends meet. I live in a small one bedroom apt i cant afford to get anything bigger for when this child gets here and idk how much he is willing to help me cause it all has to go threw her first. I dont have money to go get a lawyer and fight him he brought up the options of abortion and i have never been for it but im not gonna lie i have considered it. I just wish i wouldnt have believed what he said cause i would have never tried to make a child with him. i am so confused i would appreciate any advice put please be respectful with your words