Can a friend repossess my car out of anger?

[MBCarGirl]

I am buying a car from a friend with a mostly oral agreement. I have a digital copy of all payments that I have made, and I am up to date with no late payments. Recently we had a disagreement and he is not talking to me now. This is my only car, and I feel he would be devious enough to repossess it out of anger just to get back at me. Can this be considered as Illegal Repossession in the state of Michigan even though there is no written lease that we signed? I pay monthly and have records of it. I also have been paying for any repairs that the car needed while I have been driving it. If he repossessed it, could I sue for the amount I paid as well as to be reimbursed for all the repairs I paid for? Lastly, I can provide Facebook messages that relate to car payments as well if need be. Not sure if they'd help, but it would show that there is a purchase agreement between us.