Should I feel guilty for sleeping with someone other than my FWB?

Hannah

I’ve been sleeping my FWB for about 6 months, we were really good friends for about four years beforehand and he’s stuck by my side no matter what, I developed feelings for him but he made it clear that we were going to be nothing more than FWB.

One of his best friends just so happens to be my high school ex. My ex decided to invite me over to hang out, which ended up in us having sex. It at the time felt like the breakup had never happened, that we had bounced right back to what we were.

Driving home that night, guilt filled my stomach.

should I feel guilty about having sex with my ex? Should I feel guilty for sleeping with someone other than my FWB? Should I tell my FWB?

Why does it feel like I cheated?