I didn't know before now that he smokes pot. This makes all his recent behaviour fall into place. Pot rewires the brain when you take over a sustained period (and sometimes when you don't). From you described sounds like his brain is pretty rewired to me. You say he has done this off and on for years. Try to remember if this was also at times when he was trying to withdraw from the pot. It could be very significant. Sounds to me like you need to throw a drugs worker into the pot of help that your H is getting.
Please be careful.
Me 43 XH 45 M 2.7.88 Divorce 7.10.09 Kids D20,S17 & D15