Don't think you're crazy, for venting. If you've gone completely nuts, you wouldn't have even took the time to share how you feel. The burden feels a lot heavier than the hope you carry but whatever sanity you're gripping on to is obviously still there preventing you from going off - whatever way that might entail, for you (saying 'fuck it all' and leaving everything).
You want help and that's....what....matters.
GET IT!
Do what you have to. If being a daddy is the only thing keeping you somewhat leveled; that's a fuckin' lot and clearly well worth helping, yourself (as it should!).