Blowing, if you want out..then by all means, it is time to get out. Al-anon can help you come to terms with what has happened in your life to bring things to this point. And you will still be sharing custody.
It took me a good long while after finally getting OUT of looking at what happened, studying, reading here and elsewhere to recover from living with active alcoholism. Getting out helped hugely and immediately and I will never say differently. But I still needed to process things because my thinking and emotions had become so warped from living with and adjusting to and trying to manage insanity.
Will his paying his child support be enough for you to get by without him there before August?