vaya, i can't imagine how it felt for you knowing he had 4 ODs and hospitalizations. and why you would want to ramp up your involvement.
sadly, your AS doesn't seem to GET IT. he keeps wiggling off the hook and trying to do it HIS way, which means continuing to use. the last minute switch on the recovery plan is classic addict. he knew if he went INpatient, he'd have no access to drugs....but if he appeared compliant and chose OUTpatient, he'd be free to use at will.
until HE truly sees the life and death choice, your intervention will be limited at best. he doesn't care about birthdays or normal days or even the effort you put in. he will tolerate your interference as much as it still enables him to use drugs. he'll do the bare minimum to give you hope
you said he can't be at your house if he used.
he used in your home. on his birthday. disrespecting your "rules". but you aren't dealing with someone who cares about rules, or even a mother's love and tender heart. you are a means to an end.