herewegoagain1,
It sounds to me like he may be on meth again - the hysterical happiness, the weight loss, the craving for sweets....just my opinion.
As for yourself and your daughters, I think leaving or not is a decision that you need to make. I hope that you look for some support though, ASAP - be it counselors, nar-anon, relatives, whatever. It sounds like inpatient rehab would be ideal for him. Get some advice from professionals....you shouldn't continue to try to do this alone - it is too much.