Hi and welcome. I'm relatively new to posting but have been lurking for several years. You have found a great group who will give you tremendous support and comfort and advice.
My daughter was somewhat like your son in being nasty, vile tempered and downright hurtful. However, she did not have autistic behaviors. I found I had to find a way to determine what was in her control and what she truly couldn't help saying and doing. The more I understood about her behaviors, the easier it was to tolerate them. It also made it easier for me to hate the action but love the child.
Once I figured that out, it was easier to give her the praise she so desparately needed. I could praise her for not saying what she was thinking, thank her for cleaning up the mess she made (after asking her three times -- had to wait for her to transition from NO mode to thinking she was doing what she wanted) and honestly reward her with words and hugs when she did well on her own.
Others will come along and give you more and better advice. They'll also have a ton of questions for you.
Good luck! You're not in this alone.
