I can really relate, although I can't imagine living with opiate withdrawl every month for years! Wow! 4 times has been enough for me.
We tried to seperate last year, but my husband had no car, job or place to live, so I took him back on a provisional basis pending on him cleaning up his act. He did better for awhile, never got a program but I think realizing he didn't have a pot to **** in made him motivated to save our marriage. Now we're right back to where we started. He complains about me having all the "power" in the relationship, but its not my fault he's never finished school, quits his jobs, and spends his energy feeding his addictions while I've been working hard and have a great career and doing well in grad school.