Driver, my brother is, in fact, bipolar. He knows this, and accepts it, and chooses not to manage it. It's not that he's done wrong things, we all have, it's that he continues to do the same wrong things over and over, with no regard to the suffering he causes. He never sees anything as his fault, and won't consider things he does are wrong. He's had opportunities for support and treatment and refused them. He believes it is something he can handle himself, and is handling himself, though nothing ever changes for him. He calls his depression "sin sickness" and believes it's Satan come against him. These are not just delusions, he chooses to believe these things, and I guess refuse treatment, because they provide a way for him to never face the wrong that he's done. I think I can assure you that you have little in common with my brother. Whatever you went through, you saw it was wrong and you do whatever you need to to make it as close to right as you can.
Nothing is unforgivable. I take comfort in knowing that he does still have that Spark, and that someday, he may realize it. I've seen it, but I don't think he even knows it's there, because he's afraid to look.