WIBTAH for my cousin misbehaving at an event that I "orchestrated" ?

My cousins are spread out around the country - our parents/aunts/uncles have mostly passed away. We are now all in our 50's/60's +.

So I wanted to visit some cousins in another state, and in our cousin chat group I suggested maybe it would be nice if some other cousins went at the same time, as we don't come together often and never as a group. So some of us did that. They all made their own travel and accommodation arrangements

We stayed at the home of one cousin who hosted us (HC). To cut a long story short, it turns our one of cousins is unhinged (UC), behaves badly at times (I didn't know), and apparently knows a family secret that would (if she blabbed) create problems for HC's now very old parents. I didn't realise that UC was actually unhinged.

As it turned out, UC did misbehave, but didn't blab. UC an HC had some kind of big argument, that I did not witness. Talking about it later with HC, after I got back home, HC told me that if UC had blabbed, HC would not have forgiven me. I asked why it would be my fault, HC replied it was because I had "orchestrated" the whole trip. Nobody objected to the trip prior.

WIBTA if UC had blabbed? I can't see why it would be my fault - by HC was adamant.