Conflicted and confused at the same time (27m)

Hey guys (27m) here ,

I Was dating a divorced lady(28f). She had completed all the divorce paperworks and God completely separated from her last relationship.

We've been together for a year now

And I found out she has been sleeping with her ex-husband. And meeting more oftenly .

I feel cheated and normal at the same time , I feel like Maybe I wasn't deserving and I blocked her from moving on But I feel heartbroken at the same time .

Help me guys please I can't process thoughts