HenDog do you think some controlled socialisation with stooge/teaching dogs might help? I have heard great things about these people although haven't been there myself as it's too far for us to travel. I know quite a few people who have taken their dogs to them though and had very good outcomes. I've also spoken to them on another forum and they seem lovely.
Totally understand the tears - been there myself through two reactive rescues. Your user name is very apt - having a reactive dog can really take over your life.
My current lad has gone from being reactive to off-lead dogs as an older pup, to now bouncing and barking when he sees dogs running off-lead, because he wants to go and play with them. Daft mutt! Fortunately, most dog people can tell the difference and he will respond to cues to stop, but some people are still worried by him, because he's far from small and has a big mouth a loud bark.
We did a lot of BAT training - basically keeping him under threshold a long way from other dogs and giving him the reward of retreat if he was able to look away or offer a calming signal. Also lots of counter-conditioning, treat-bombing whenever another dog came into view, to change his associations from anxiety to cheerful anticipation when he saw other dogs. He's two years, three months old now and has just amazed us by being really good on our beach holiday. Last year was a nightmare with other dogs on the beach, this year he loved it.
Now if we could just crack his separation anxiety we'd be laughing. 
You sound like such a lovely, committed owner. You'll get there and the rewards for both you and your lovely boy will be huge. 