Dubsyd, you've received excellent advice above, and I'll second DeeDee's advice specifically. Plus send you a big cyber-hug!
I'd also add that ages 6-7 is a significant development stage for *all* children - not just for children with challenges. It's the age when children are starting to realize they aren't "attached" to their parents but exist as separate human beings, and it can be filled with challenging behaviors for even the kids who've been completely easy going up until that time.
It's also the time when, for my own kids who had some type of undiagnosed LD or other challenge such as a vision issue that behavior was really a huge challenge. My dysgraphic/dyspraxic ds had been the most mellow kid who ever lived (for the most part lol), until he hit first grade and then he seemed to turn into a raging upset kid most of the time because of the stress of having to write in school and talk to teachers. My dd who had severe vision issues had what appeared to be on-again off-again behavioral and sensory challenges all along - up until her vision issues were diagnosed and treated - which didn't happen until second grade when she was able to tell us she couldn't read what her teacher wrote on the board. It's not unusual for parents and teachers to *not* see these types of issues until first/second grade when the type of work students have to produce in school changes up a bit. With gifted kids it may be even longer before challenges become apparent, and with a child who has a history of behavior challenges, it may be easy to assume it's all behavior - when there might be something else going on at the same time. With your ds, pay attention to when he has behavioral issues - over time, you might see a pattern.
The last thing I'll add is that as our kids get older, it really does get easier - their ability to communicate what it feels like to be *them* increases dramatically as they move into middle and upper elementary school, and that helps *so* much with parenting through this tough stuff.
Hang in there - and when it gets really tough, take a break for a few hours. Indulge *you* - do something you love, something that's fun just for you, get your mind off of parenting for a few hours. When you come back to it, do something that's fun for you and your ds together.
Best wishes,
polarbear
