There's always open adoption. You can still visit the child and have updates or whatever, but you'd be like the family friend, maybe an aunt or a cousin, something like that.
I wish my sister had done that. You'd be giving your child a better life than you could give to it, but you'd still be able to see how well the child is doing. Then when the kid is "of age" (whatever the adoptive parents choose) they will probably tell him/her that you are their biological mother.
I don't even remember where it came from but I love the quote, "it's easier for me to kill you than to wave goodbye." because it sort of simplifies the way I see things. I hope i'm not too pushy about this.