My online groomer transitioned, is it correct to use her pronouns?

Not going into big details here, but I met a 17(M) guy online when I was maybe 10-11(F). I came out as gender neutral when I was 14(N) and I found out the person was now using she/her pronouns. I still sometimes accidentally use he/him while talking about her in my head.
While the recent Kris Tyson situation sparked a lot of debate about this, I now need people's opinion on this. - I feel like it's hypocritical of me if I don't use her pronouns, especially because I'm trans.