Well...
As someone who blamed himself for everything since the beginning of time, let me say this:
Stop it. Right now.
You don't have that kind of power.
Here's my take.
It's not that God can't forgive you. Whatever you've done, God has forgiven far worse.
The issue, I bet, is that you can't forgive yourself.
I'm not trying to be cruel. Just the opposite. Be compassionate with yourself. I'm sure you didn't sit up all night devising ways to ruin those around you. If things didn't work out ... well, that happens.
Unless you murdered people, sold drugs to schoolkids, or stuff like that, you're a pretty normal person.
I did a YouTube episode about this very topic:
https://m.youtube.com/watch
To elainer12. Since you are deep in your distress over your past, that is t'shuvah (turned around). You are already repentent. Therefore, God is with you in your repentence, and, so to speak, already in the process of forgiving you. The next part of t'shuvah is to live your life in accord with God's teachings. Study. Prayer. Acts of kindness. (The last one is really healing).
The thing NOT to do is get stalled in guilt and not live.
How can any of us live a life without making mistake after mistake. Theater of the Absurd (and maybe Woody Allen) would say this whole thing is one big mistake.