Don't put all the responsibilities on your shoulders, you have had enough and you can't handle anymore. If you really want the baby to have a good daddy, let him learn and stand by sideline to advice, not do it for him. And there is a mother too, she will love the baby more than you do, don't worry too much.

I can't advice on that statement...sorry....I'm struggling too, but you are not alone to feel this way. If anything to advice, hang in there for your grandkid, if you go, the baby will have one less person to love him/her.