I am very sorry for your loss, Lisa. I cried when I read your post. I can't even imagine the heartache and guilt you feel. (big hug)
ALL sin pains God. Stealing that candy bar when you were a kid was a sin. Telling your husband that you paid less for that new dress than you actually did was a sin. Snapping at your kids when they are driving you up a wall, is not speaking lovingly, and is a sin. Looking at someone with lust in your heart is a sin. A sin is a sin is a sin. No sin is "wronger" than another sin. I am not making light of abortion. It is a horrible thing. But God doesn't differentiate sins the way we do. As Christians, we are supposed to imitate Christ. We need to look at sin the same way He does and not categorize them into levels of wrongness.
Believing that some sins are worse than others is dangerous. If one sin is bad, and the next is badder, and the next is badder still, you can go down that line to a point where a sin is so very bad that it can't be forgiven. That puts a limitation on God's Grace. That says that His death on the cross was not 100% sufficient.
It is dangerous going the other direction too. If this sin is not as bad as the previous one, and the next sin is not as bad as this one, and so on down the line, you go from very bad, to bad, to only a little bad, to not bad at all. You will be calling sin good.
God forgives you. He said He forgives ANY sin, if you ask Him. If God forgives you, you are going against Him by not forgiving yourself. He commands us to forgive others. If we are to love our neighbors as ourselves, we ought to love ourselves as we love our neighbors. He wants you to be free. He doesn't want you to beat yourself up over it. He already had the Romans beat Him up for it. If you think about it that way, you will love Him instead of hating yourself. Love is better than hate. And focusing on Him is better than focusing on you.
I preach a lot better than I practice. Don't we all? (Poster #46 in this thread needs to read this too

)
Be well,
~A