I'm glad I could help, your story really touched me as I had an abortion because I didn't want to be forever connected to an ex.
A child who grows with an absent father will always be different (not better or worse) from one that has their father (and mother) close to them - whether their father is anonymous to them because they came from his sperm donation or because he wasn't involved or was perhaps not there because he died.
Had you not had the abortion the baby would grow and still not know their father, or if they did they would know they weren't born into a happy situation for you.
You don't have to be a single parent, certainly not aged 35, you have time still. I got pregnant at 37 and though fertility drops the closer you get to 40 you don't really need to consider being a single parent and going the sperm donor route unless that's absolutely the route you want to take, by choice not down to circumstances if that makes sense.
It sounds to me like this relationship, the pregnancy and the abortion has thrown up some issues for you and I would encourage you, if you can, to seek some therapy so to process this with professional guidance. Dating probably isn't a top priority for you right now and with lockdown (if you are UK) it's not on the immediate horizon either! Maybe take this time to start processing what's happened this year and find a way to heal a bit, your next relationship will thank you for it.
You won't ever forget the abortion but you don't need to make amends and you don't need to feel guilty. Your choices are yours to make and I hope what comes next is positive and hopeful. Good luck to you OP and take care x