I'm really sorry, Honey-Lilac. What a terrible decision to have to make. From your posts, it seems that you are quite thoughtful so I don't know if what I am writing is going to add anything that you haven't thought of already. I do have some thoughts on grief and regret that I'd like to share. Regret doesn't always mean that you wouldn't do the same thing again, it also can mean that you wish things/situations could be different so you could make a different choice. Does that make sense? You've not written a lot about it and I don't want to presume to know but your feelings about having an abortion seem to fall into the latter camp: you want the situation to be different so that you could make a different choice. That part of regret has a lot in common with grief. Grief hurts and can rip your heart out but you can come through it, too.
I wish you and your family the best.