Maybe he does need a father figure in his life. Have you given your latter ex a chance to rebuild a relationship with your son?
My son's father was emotionally/verbally abusive and was becoming physical - my son was only 3 1/2 at the time, but was starting to act like his father. I decided it was my responsibility to get my son out of that situation no matter what it took. It sounds like you need to move to another area because he has much further to go school-wise, he cant stay in the house forever. I would be extremely careful and cautious of who you let into your son's life (male figures) because I can assume he must have major trust issues as my son did for years. He needs a loving and oatient role model who can make him feel at ease and cause him to trust again, whether a family member or a good husband.
I am so sorry for you and him ,does he have plenty to do, sometimes children who have been abused do well with sports does he get out to play ball and other outside activities, any friends his age nearby to befriend, when they are home schooled they still need some social interaction. He is upset ,plenty of positive attention, read books to him so you fill his thoughts with good things he can dwell on. Board Games are good at 7 he would probably enjoy scrabble , even Monopoly , card games are also fun, put some music on when he gets upset, dont feed into it let it pass with out too much paid to it. Let us know how you are both doing ,we would like to hear.