The past is released through forgiveness. Understanding why can bring compassion, which is good. But it really requires forgiveness to be free from it. True forgiveness, where in your heart you forgive them. Don’t hold any resentment toward anyone, it only hurts yourself.
Someone such as your parents, who didn’t have the self will to overcome their own difficulties, doesn’t mean they didn’t love you.
Thankful for the good times and forgive their struggles.
Although I believe that all difficulties can be worked through, it requires believing in yourself and the self will to change habits which can be uncomfortable.
For Paul’s thorn in the Bible. He only tried 3 times before giving up. And somethings God wants us to work through because the teaching comes from working through it. Having it taken away would have robbed him of the lesson he could have had by working through it. But we don’t know what it was, and he tried his best. Which is the most that can be asked of anyone.
Compassion for others to love others as yourself because we are all part of God, thus we all are one. Any feeling toward another person, that feeling it also about yourself. If you dislike someone, that will be experienced as disliking yourself. It takes practice at first to feel the subtle emotions that are created by every thought you have. But they are there. (And they build up overtime if they aren’t felt). Which goes into the importance of thinking positively as much as you can.
Negative thoughts create negative emotions.

