Need advice on a tricky admission situation

So I was recently arrested on a trespassing charge. The charges and case were dropped, however, the arrest is still on my record. The thing is, I have already been accepted to a university and on my application I wrote I was never in any legal trouble (I can’t remember if the question had to do with just incarceration or all arrests in general), and technically everything on the application is truthful since I applied and was accepted months before the arrest.

What I’m now concerned about is whether I have to tell the university about the whole situation. I tried looking into the fine print of the school, FAFSA, and my scholarships and none of it is very clear as they tend to only talk about current students and applicants who have been arrested and charged. Some documents imply that incarceration would make you exempt from a grant but then also say they can take away the grant if they find out you lied on your application. So where does that place me if I never lied but still had my circumstances changed? Especially when that change is hardly substantial in the eyes of some people (arrested but never charged, tried, or incarcerated).

I’m not going to lie about my circumstances, but right now I’m not sure whether omitting or admitting the change in my record is the better call.

It the charges and the case were dropped, it seems there were no grounds to arrest you in the first place. I would say nothing.