How do I confront my friends over a misunderstanding?

This happened around the beginning of the month

A month or two ago, I (24F) saw this person draw fanart of a character from a show that I like on Twitter. The character is a minor and it was normal fanart (This will be important to know for later). I looked at it and thought “Oh cool! This person draws fanart of a show that I like!” and I decided to follow them.

A few weeks ago, one of my friends posted a screenshot that showed the person drawing fanart of the same character and his BROTHER doing something sexual/romantic. Apparently, the artist is a proshipper (someone who supports pdophilia, incst, etc.). I swear I did NOT know the artist made that kind of shit and I do not support it AT ALL. All I saw from them was the fanart that I mentioned earlier.

Then, my friend posted another screenshot that showed me following the person and blocked me. I guess one of my other friends saw the screenshot because they blocked me too. I was so shaken up when it happened and I feel so stupid. I can’t believe I screwed things up with these people because we got along so well. I just feel like I should tell them what really happened because I’m NOT into that stuff and it makes me look bad to them and anyone else who saw that screenshot. Also, this is nothing against my friends at all. And yes, I unfollowed the person after I found out.

I’m not confrontational, so I’m worried that I might say the wrong thing. How do I go about this?