Something that has helped me in the past is, "Resentment is like drinking poison and expecting the other person to die."

I feel like I've been where you are. Seeing an ex be so happy and so free and having the life that could have been had they bothered to care about the relationship and love you as much as you loved them. It's easy to let ourselves live in the shadow of their success, and let their happiness feed the monster that is our depression and self-loathing.

I found it was important to find a way to establish myself again. To establish my identity. And to work with a therapist to understand that life doesn't happen the way we plan. There's a joke that I like that says, "How do you make God laugh? Tell him/her your plans." I think a lot of us have dreams for what our life will be, for what marriage will be, and for what our family will look like. It seems like it rarely works out that way and we have to give ourselves permission to struggle and know that we're not bad or wrong or failures for not meeting those unrealistic ideals.

I'm so sorry for your loss and for your pain. I can't imagine how painful it must be having lost custody. I do know from my own experience what it feels like to be so hurt and betrayed. Divorce is a type of trauma, and it takes time to recover and reclaim your life. I hope you find good support and courage along the way. Best wishes.