questions about METH my boyfriend is in trouble?

The question isnt should i leave him…because I know that is an option. I have tried. it has not yet come to that, so my question is more for the meth user. or someone who has recovered from this…what are the chances od a recovery? My boyfriend is divorced from his ex wife has 4 beautiful children. This man is very spiritual believes in God, he has the intentions to stop using but struggles and uses. when he uses he binges leaving for weeks and lately months at a time straying from me his now girlfriend. I do love him dearly and wish for him to be well. He is such a great man when he stays away from meth. I know i can leave him. but should i? this man is my best friend. should i just give up on someone even tho they want to get out of this addiction…he has no more family support, just me. he has no job no food to eat. he does still have a roof over his head and a car FOR NOW…but my questions are where does one like this go for help, if he is willing…what does rehab do? or is it just a waste of money. i realize that he needs to help himself but what are the steps I should take if i choose to help him…i know standing back and letting him fall is an option. but is there possible another way…?