This is a sad tale. Nothing worse than a dog with potential agression issues.

Have you considered taking some train g (you and the dog - not sending him off somewhere) with a professional trainer? there are some decent ones and you might be able to get some really good handling hints.

The problem is that he is a strong dog, and if push comes to shove and someone gets bitten - even if a total accident - your dog will be blamed and you may be forced to give him up.

There are some rather good books on training and dealing with behaviour issues thta I used to have. If you like i can look for them and send you the names.