Holy crap...nightmare situation is happening to me. Student said I "laid hands on him". I had admin pull me aside today to investigate. WTF do I do now?

I'm a long term substitute. I've been filling in for a resource teaching position at a local high school. I have this one student who has been leaving class before bell rings. Our rule is to not allow students to leave before bell. The first time he did it, I yelled out to him to get back to class. He just runs away. I filed a referral with the office and saw nothing happen. He does it again the next class period. I yell out to him, he just runs away. I file ANOTHER referral. Nothing happens. Then, the next day, I'm asked by the office supervisor to fill in for a period during my prep period. That kid is in the class. So, before the bell rings, I go near his desk, and I tell him, "Ok, stay in your seat before the bell rings." Our bells are a bit late. The time changes to the time they are supposed to be out. He stands up (he's a big kid, over 6 feet, easily bigger than me), says, "Get outta my way get outta my way!" I'm close by, so I brace myself. He then pushes against me and I have to push back otherwise I would fall. But, I quickly move out of his way and he runs out of the classroom. The class lets out and I see the instructional aide. I ask her, "Does he often just run out all the time like that?" And he says, "No, this is the first time I've seen him do that." I go back to the office to fill out a third referral for him.

The next day, I see him in my class. I ask him to come outside for a discussion. He comes out, and I ask him about that day. I said, why did you just run into me? He then said I pushed him. But, the thing that got me was he said "EVERYBODY was talking about it after."

That was about two weeks ago. I was not supposed to come back to teach the class this week because they hired a full time teacher. But, that teacher is in limbo. So, they asked me to come back. I said, "I really can't because I have other obligations." I really do. At this point, I really have no desire to be a teacher at this level nor substitute teach anymore. It's just not for me. I'm also finishing up grad school and want to look for other jobs. But, they pleaded for me to come back for just this week.

So, today, as I was leaving, the asst principal asks me to see her. She says there are allegations that I laid hands on this student. She wanted to hear my side of the story. I told her what happened. I told her what I said here. I also said that before this, I long term subbed at another school in which the teacher was pulled by the district out of the class because of allegations that he hit another student. It was supposedly a shoulder check or something like that. So, I know NOT to touch a student. She said she would need to talk to other students in the class to get their side. I already know, based on how he said, "All the students were talking about it." that it's not going to go my way.

So, my question now is, what do I do? The other teacher that supposedly hit a student, I found out, was returned to his teaching post. At this point, though, I really have NO desire to sub or become a teacher. This was something I've been realizing even way before any of this happened. I'm just wondering, now, what are they (admin/district) likely to do? Initially, my thoughts were they are just going to ban me. Which, I really don't care. But, now I'm wondering if this could go further. Like, could they file a lawsuit against me? I'm getting paranoid. I mean, they know I'm not going to be there anymore. Why are they running this investigation???

edit:

Should I just call the asst principal and ask what their intentions are? Or, should I contact the union and seek some advice/representation? I'm not looking to fight for a teaching career. I am hoping that no lawsuits come out of this. By the way, I am in California.