Feeling good but scared at the same time

It's weird though. After I know my ex is currently fine, I feel upbeat. I mean I should feel pissed because they were toxic to me. But I feel good. I'm happy about that fact. I don't know if I really feel that or I'm at the cycle stage that chemicals in me are stable, so I feel good overall. But my friend also says that I look happy compared to me in the past. It makes me feel a bit scared... I don't know if this means I'll crash hard in the upcoming future... (like what going up goes down). Did anyone experience this?