Thats the spirit OP.
Vent on here, cry to us, be solid as a rock towards him.
I would still set up an email, offer contact eg 'contact every other sunday 10-5, starting x day, arrangements to be agreed via this email.
I will check emails weekly, on mondays.'
You set the tone and the pace.
He will either step up, or not.
As will you!
Im a lone parent, it was so hard at first, i was even scared at night to start with.
My DD has just aced her GCSCs and is loving 6th form and her part time job, my DS is a happy 11 year old, has a party to attend tomorrow and a friend staying tonight. Ive just told them off for being noisy 
I have a lovely home, a job i love, a ton of friends, and enjoy life.
I made some bad decisions but have dealt with things so they have worked for me.
Mumsnet has been a huge source of strength and inspiration to me too.
You dont need him.
Soon, you wont want him either.
Did you look at chump lady?