Hi S.,
My heart just broke when I read your post. I have an 11 year old son and home school as well. I know exactly where you are coming from. You've had a lot of great advice.
I found that therapy does not work unless the person who needs the therapy realizes it and WANTS to change. Most men in these situations feel they are doing the best they can and indeed in most cases they are. So, it is really up to you.
Sports like Tae Kwon Do and swimming are great self esteem builders (TKD will also empower your son to never be afraid of a bully, it has done wonders for my son. ) I encourage you to enroll him in both over the summer. There are other "individual" sports like fencing. Even tennis and golf can help build self esteem. Boys always need a physical outlet.
I don't know if he gets frustrated, if so, a punching bag hanging in the backyard tree is a great tension release, so is a trampoline.
Try to make your house the "fun" house. Invite friends and their kids over once a week for a potluck or pizza and you will see your son begin to blossom. By extension he will be the "fun kid".
If your family volunteers, that is another great way to build self esteem. You and he can volunteer to feed the homeless ( they are looking right now for more help at The Bridge which the Stewpot will service, in downtown Dallas) . You said he is good with animals and the elderly. Both great venues for volunteer activities. My mother lived with us the year prior to her death and I saw my son grow in ways I never expected, just looking after her and going to appointments with her made him feel so grown up, in charge and self assured.
Don't worry, he won't lose his tender heart. God gave it to him and that cannot be taken away or lost. He has a tender hearted, loving and nurturing mom and is no doubt already wise enough to realize a tender heart is not a "guy thing or a girl thing". It's a people thing.
If there is anything your husband does, golf,chess, walking the dogs, biking, even just going to a movie, that they might be able to bond over, try to find even one thing. I've recently got my husband to play a couple of video games, walk dogs and also bike with our son a few time a week. Dads like this are desperate to bond, but so much reminds them of their childhood and I suspect they feel overwhelmed and inadequate much of the time, bound by awful memories.
If a one on one activity won't work, maybe a family game night once a week, or even just watching a dvd together.
Another self esteem builder is anything your son is good at, art, writing, building, speech,
get him involved in a group that will nurture these things.
As a home schooler you are aware there are great coop classes he can get involved with which can be a great way of meeting other nice kids.
Our son knows if he has an issue he wants to talk about he can see our pastor and they had a great talk that really helped him. Hopefully your pastor can act as a "second" dad or perhaps your youth minister. There are male role models all around us and our boys will see all men are different.
Please take heart, keep faith, your son will turn out just fine. If you want to email me privately, I can recommend a great TKD class.
K