What do I do

So I have a problem I have no idea what to do and no one to talk to about it, I gave birth to my daughter 4 and a half months ago (just a bit of back story) her farther and I were together for 2 years before she was born, he had always been the most amazing, caring kind partner better than I could ever wish for but 5 weeks after she was born he cheated on me and I kicked him out, we’ve been off and on since then and sleeping together too, he’ll tell me he loves me and will promise to come home and treat us right but then the next day he’ll be so horrible and leave again, he never use to be like this it’s so heartbreaking.. so a couple of days ago I had suspicions so I took a pregnancy test and I’m pregnant again, I took the test before even my missed period and it showed positive before I even finished peeing! So I feel it may be twins, I’m enjoying being a mother so far but I do really struggle due to my mental health and things that have been going on recently I’m so down, I don’t know how I could cope with a second baby let alone if it is twins but I feel so much guilt thinking about abortion, I even booked one and didn’t go because I had second thoughts but I also feel it’s probably selfish to bring new life into this situation, also only about 3 months ago I was blissfully happy thinking I had my own little family and now it’s all gone, what would you do in this situation, please can someone give me some advice do I keep my baby/babies and make it work as hard as it’ll be or do I go through with the abortion?