Forced Abortion (Sorry for the long post)

Buckle your seatbelts, this is gonna be a long ride... 
I had my first child at 18, and of course it changed my life in many ways, but everything had a way of working out for the best. When my daughter was 8 months old, I found myself pregnant again, and couldn't bring myself to accept the idea of having another baby so soon, which brought me to the decision of having an abortion. It wasn't the greatest feeling, but it was the right thing for me to do at the time.. 
This was a year and a half ago. Since then, I've broken up with the father, and we're on great terms so I have no issues there.  I've been with a new man for not very long (about 6 weeks), and unfortunately had some issues with my IUD resulting in my third pregnancy... It's been a crazy week since finding out, and I've been terrified and confused amongst all sorts of other emotions. This new guy was so great, and I expected him to take the situation maturely and with an open mind, seeing as he is quite a bit older than I am... Wrong! He's been awful, and selfish, and pushing his agenda without an ounce of empathy or sensitivity to my feelings (despite his "efforts"). There have been threats, and attempted bribery (he offered to PAY me to have an abortion). I know it is most likely the right thing to do at this point in my life, but I can't help but consider other options, seeing as I've been through it before and I love my daughter so much. She would be 3 years old by the time this new baby came around, and that's a decent age gap of you ask me. I could make it work, no matter what. 
Despite all of this, I gave up trying to argue and agreed to go through with a medical abortion; I even have an appointment to follow up and receive the medication next week. But I can't help but think I might not be able to go through with it, and I'm terrified of what my partner will say or do if I can't, or if I need to wait and think about things longer. His Idea is to "get it over with as soon as possible", but in reality I have over a month to make a firm decision either way. Anything I say about the pregnancy that isn't related to abortion has been dismissed and shot down, which has been awful because I need to be able to rely on my instincts and consider all possibilities.. 
Anyways, I needed to get this off my chest and find some advice or support from a third party, it hasn't been easy to handle.