I commend you for asking that question here on YT!
I normally don't advise this, but now I have a question for you.
Did you ever think of re-homing him? I'm sure that there are a lot of people trained who would be willing to adopt him to work on the agression, and give him extra TLC. Please know, I am NOT trying to be mean to you or say that you are a bad mommy. That's not at ALL what I'm saying.
I'm just saying there are other options other than placing him in a garage. But, truthfully and ultimately, you have to do what's best for you and your family. I hope you find a happy medium!