Down in the dumps
You'd have a hard time od'ing on codeine. I'd bet ten bucks the acetominophen in the pills would get ya first, and that'd be a slow, painful, miserable two days or so while your liver and organs shut down. Think of how unpleasant that would be.
I'd bet ya twenty bucks that your daughter will be waaaaaaay better off with her father around. She might consider her past fucked up too, when she gets older, if she had a father whose fly-covered body she found covered in vomit when she was young, and that was followed by what might wind up being a nightmare childhood in foster care with who-knows-what for parents.
Get thee to a doc quickly my friend, get a script for some antidepressants and in a couple weeks you'll be damn glad you did. Get some therapy too. Whatever the fuck happened in your childhood wasn't your fault so don't go beating yourself up over it. Blame the fuckers that made you feel this way now. If there's a problem with physical or sexual abuse, alcoholic/addict parents, post traumatic stress disorder, anything... do a google search and you'll find a relevant forum and some local numbers you can call for help.
I don't know where your friends are, but some of them are in the right place if they're suggesting you go get some Prozac or something. This won't go away on its own. You need the services of people who spend years in school so that they can help people out. That profession exists because there's a huge demand for it. Don't be afraid to take advantage. That's what they're there for.
Codeine is for headaches, take a couple for that. Don't use it do something you'll definitely regret.
Hang in there. Go get some help. How old is your daughter?