It's nice to see you posting again, I'm sorry to hear that your two boys still aren't getting along.
I'm sorry you have to rehome Havoc but it sounds like it will be a good arrangement for him to live with your parents who love him and you can still visit him often and give him some one-on-one attention. I hope that Toby will behave better without another cat in the house to compete with.
I know you have tried everything to make them get along, I hope the new arrangement works out.
Please post some new pictures of both of your boys and check your PM's too.