Finding I turn red around certain people?

I made a post a few weeks ago about turning red around my S/O’s brother. I’ve been with my S/O for over 5 years and it hasn’t happened until recently.

Now I’m noticing it happens with others too.

My S/Os brother is coming for a weekend and I don’t know how to stop from turning red. I think I’m embarrassed over a joke he made towards me a year ago.

Any advice?