They won’t be able to forgive you. They will want to, but they won’t be able to.
When someone genuinely thinks of a foetus as a baby, then an abortion has the same emotional impact as smithing a week old newborn in its crib.
Imagine the grief that pregnant parents go through when they have a miscarriage of a wanted baby. Even if they were pro-choice, the fact that they wanted the baby meant it was alive in their hearts and minds, and so their grief was real.
Your parents will have this grief, and you will be the one who deliberately caused the miscarriage.
Do not do it.
No matter how much they love you, it is not something that a person can forgive if they think of it as a baby.