Undue pain? Who the f do you think you are? Who are you to presume anything? In no way and at no point did I ever even remotely state that my child was not well taken care of. I work my ars off to ensure that he goes to the best private school on long island. He is there full day and any cases that I have after his school time, he comes with me. If you have issues with how you raised your children, keep it to yourself. And as for his father. You're absolutely right. Let's send him off to heroine addicted father who not only beat me, but beat his child. And before you jump the gun... I left. I left the relationship and tried my hardest to keep that sob out of my child's life. The only reason he's even remotely in my son's life is because the courts have ordered it.
All parents have regrets. None of us are perfect. If we were we certainly wouldn't be posting on a "soberrecovery" website. Being a single mom is incredible hard and draining. Sounds like you've done everything you can to provide for your son. There's no shame in being emotionally drained, depressed or needing help. I encourage you to find a counselor or see a doctor to get help for your depression. At least talk it over with someone on a more personal level than on the internet.
Get help. You are worth it & your son is worth it. It's not to late to fill that void.