I don't think there's much relationship to salvage when your father has taken to committing actual felonies against you.
I really don't know how to go about fixing this either but I suspect if you get someone administrative at the Post Office and tell them exactly what's happening they'll be able to guide you in a direction. At worst, you'll only waste your time.
As someone who had a piece of shit father who stole from him and ruined his life, I'm going to say sue the fucking shit out of him. Take him for everything he's stolen from you and then some, and never speak to him again.
I was sad when my father died, but don't think for a minute that I forgot the shit he did to me. He stole thousands in saving bonds from me to buy drugs and I have a pretty good feeling he may have also had a friend 'steal from him' and sell all of the things he 'stole' for drug money when I was a child. He deserved to get kicked in the ass for the shit he pulled and the only thing I regret more than my dad dying while we were on bad terms is my dad dying without ever really feeling karmic retribution for making my life miserable for my childhood and adolescence.
It's easy for those of you with good relationships with your parents to cast a judgemental eye, but I don't wager your father cashed in your college money so he could buy a few more days worth of heroin.
Actually, my life continues to be ruined to this very day by evilly incompetent parents, who have routinely put their own needs ahead of mine. Thirty years and counting. I must watch as they do the same to my only brother, who still remains hopelessly ensnared at 26*. College money? Shit, that's nothing. I've seen
millions wasted (including college money for myself AND my brother AND further college money I gave to my brother afterward, not that that was all that much).
And yet, while I would never say never, I still do not recommend such a strong course of action without very serious consideration. Not that serious abuse should be taken lightly, or brushed off with a cliche that goes back hundreds of years but lawsuits, restraining orders, legal charges and other, serious and permanent severences with one's family are simply not to be undertaken lightly.
*
I have offered him asylum, but he has declined. Everyone must make their own choices. Such is life. Bleak and nasty. EDIT: Warning - while you were typing a yadda yadda I also agree with JD. I hate to be rude about this, but honestly there's been a litle too much "Oh noes I'm doomed" and all too little action to take control of your situation. It's like when you couldn't move the bed. You just threw up your arms and despaired. A solution was presented that was simple and practical. I don't know if you took that advice, but given that you're still at home, I'm not optimistic.
You need to take the helm and seize contol over your own life. Whether this means going for a lawsuit or just moving out, you need to stop dithering and get your shit together. You gotta think for yourself and act for yourself.
But maybe you're like my brother. Well, I've said my peice.