BlueFish,
Please try not to be so hard on yourself. With regards to your baby, and as Lee said, you did what was best for the baby at the time. I cannot imagine how painful that must be, but try to take heart from that fact that you have given that baby the opportunity for a better life than you were able to provide at that time.

You now need to concentrate on yourself, and getting better. You made the right decision to leave three years ago and now have the opportunity to live your life as he is now living his. In time, I'm sure you'll meet a decent bloke and start a new, stable and happy family of your own.

My thoughts are with you.