Okay, this is a serious situation. I would be angry, too. Any one of us would be hurt. Betrayal is the worst thing one can do to another. That being said, here is my input:
I don't know what your relationship is with you father. I lost my father 2 months ago. He had congestive heart failure, diagnosed in 96, given 6 years from the doctor, lived a good active life until 3 months ago. In one month, down hill to bed ridden, and 5 days later, he was gone. We have both betrayed each other in one form or another. The damage was extensive. We had an okay relationship, but looking back, well, I was a selfish idiot not to try to better it. Here's the thing. I knew he was going. We knew for 18 years that he could die at any moment, and 2 months later after he passed, I still have trouble believing I will never in this life hear his voice, or be able to hug him. He will not be able to take a ride with me in the F150 I just bought, and that hurts. I fully expect to see him in his garden ,or in the house every time I go over to my mom's house. While I believe in tha I will see him again, I am still having to cope right now. You are in a war. I imagine that you know full well how short life is, how quickly death can come, and how hard it is to accept it's permanence.
I'm thinking that your father, if he is normally a loving and dependable dad and there are no other conflicts you aren't telling us about, is in trouble of some kind. I would at least look at this as a warning sign, that he is in a bad situation of some sort. Dig deep for the ablilty to forgive him for this, and let him know that you still love him, and he can trust you enough to ask you for help if he needs it, without selling your things without permission.
If he's just a dead beat, he is still your father. Be the son you would want to have, even if he isn't the father you wish you had.
Godbless you for your service, and may God bless you and your father and heal both of you.