I am so sorry you are going through this right now. Read what you wrote and ask yourself what you would say if your best friend just told you the same thing.
he has not proven to be responsible, honest or all that caring. It could be the addiction, or it could be him. she is obviously no better. the problem is, you cant change the decisions either of them make, and worrying too much about them wont make you and your daughters life better. focus on you and your precious baby, if and when he is ready to really change his life and be a part of hers (or even yours) you will know. till then, go to alanon meetings and try to make yourself the best person and parent you can.
i know its easier said than done, but we can only control what we can control, and unfortunately our addicts arent one of those things. best to you!