I’m scared of my lease horse

For context, I rode and took lessons at a hunter jumper barn from 2006-2016. Moved cities, and found some horse friends to ride with from 2017/18-2021ish. Timelines are fuzzy because of Covid and I had two kids. A bit on and off, but totally off for the last 4 years.

I just barely started riding again this past month after that 4 year break. I took a few lessons, and decided to do a half lease on a big draft horse. His nick name to the trainers is jack ass. He has terrible ground manners, even when grooming. Constantly reaching to bite and kick. He is especially girthy. He is also impatient to mount and is always moving. I have been able to handle him on the ground ok, mounting makes me nervous since I’m just starting out again.

Today I came for a hack, and as I was reaching for the girth to do up on the other side he reached out and kicked me. I’m ok, yes it was hard but I’ll be fine. But now I just don’t know if I even want to continue riding him at all. Yes I have concerns that he is in pain, could be ulcers etc but he’s not my horse and I am leasing him for august only, I also just started, barely know anyone here and they warned me he is BAD on the ground.

I’m feeling defeated. I always dreamed of having my own horse, and my first lease horse is not turning out good at all. Help?