Abortion confusion

I am a 36yo mother of 4 and have just found out I am pregnant for the 5th time. I did not see myself having another child and was awaiting sterilisation and using the contraceptive pill which has quite obviously failed me at some point. My so has no info or advice to offer in the situation so I’m left alone to stress over the out come. For a bit of back ground I suffer terribly in pregnancy with severe sickness right up until birth even with the use of anti sickness meds. I also have a few other minor complications in pregnancy. I am self employed so being too sick to work would ruin me. My partner works full time so I would have my other children to look after whilst trying to work and being severely sick (I don’t see how I would pull this off but we move?) I didn’t want another child and I don’t but I have this niggling inside that is saying don’t do it. I don’t feel supported enough by my partner to feel like I can do I’m just so confused and lost on the situation. I also suffer with mental health problems which may pose a problem with the added stress of another human being to be responsible for (most of the time alone) as dad works long shifts, I don’t drive and I’m really really scared I won’t cope emotionally. I want to emphasise the fact I did not and do not want another child the reason for me questioning my choice is I feel terrible and responsible for what has happened even though the contraception we used failed. I don’t know what to do for best. My business is entering its 3rd year and is just about getting off the ground and really making big progress which would all stop if I had this baby. I just don’t know what to do an it makes me so sad any advice would be great l, what would you do in my situation? I know no one can decide for me but possibly could help me see a point I have missed. I don’t even know what I’m looking for it’s possibly the lack of any input from dad is forcing me to reach out I just feel so alone.