Claire, I'm so sorry that your boyfriend is being like this. I'm assuming that on holiday, he chose to not use birth control when you had sex? But then he just casually says he was drunk and that abortion is the only way forward? That's just awful. He knows how children are made and if he didn't want to use protection, he knew that a baby might result. It's not fair that only his wishes be taken into consideration. I can't believe he is being so unfeeling! To just say "You'll be fine," as if you're having a tooth out? That is brutal. This site has so many posts from women who are trying to recover from abortions, and when a woman didn't want the abortion in the first place, it's always traumatic. You are an equal part of this couple, and you would be the one who would have to go through the abortion-- he has no right to say that's his decision.
Let him know that no matter what happens, things are not going to be the same. If he ordered you to abort, you are no longer going to feel the same way about him romantically. If he thinks abortion is a reset button that makes everything go back to the way it was before the pregnancy, he's mistaken.
He doesn't have to stay with you, but in most countries, fathers are mandated to provide financial support for their children. You can let him know that you would plan to get child support from him.
There is a chance that once the new baby comes, he would love him or her just like the child you already have together (and hopefully your older child too). Some men have expressed relief that their partner held firm and did not abort.
Either way, you will have to decide if staying with this man who is not listening to you during this extremely important time is what you want to do. From what you've written, he's being controlling and unkind to you.
I think you meant you would need a surgical abortion because usually medical (via pills) is up to ten weeks and you're past that. They would probably do a vacuum style (suction) abortion. If that is not what you want to do, I hope you will be as assertive as you can be, and try to find another way. A pregnancy center may be able to help you figure out your options. They will also let you see the scan if you wish. I'm sorry that the man who is supposed to love and care for you is treating you like this, Claire.