My partner wants me to get an abortion...?

we have 2 children, 7yr old girl and 2 yr old boy. our son has a disability cause by birth trauma and he doesnt want another. I was on the pill but afte my gall bladder was removed it kinda messed things up. im coming up 12 weeks and have booked an abortion but after research i dont possibly see how i can go through with that kind of procedure. im not sure what to do...keep the baby and be at risk of being a single mum of three or do something that is against my whole value system and keep it all sweet at home?