My wife betrayed me.

We are together 12yrs and gos blessed us with 3 beautiful daughters.7,9,&12 yrs. On the 1st of December when I was randomly looking at her phone I came across a bunch of messages on Snapchat, where I saw more than 2 months she is cheating on me. And she cheated a multiple me nearly 10times. She told me she was going to do the Xmas Shopping. One time she said she is going for coffee with her work friends. But in reality, she carry her lover spurned in my car and park anywhere and have sex. Some days she had sex before coming home from work and come quietly to sleep beside me as if nothing happened. There was so much detailed dirty messages where they kept talking what did, how good was it….. wish do to something more crazy next….. like a lot. Praising each other body parts and all. After the confrontation, she says to me she is sorry and it a mistake, she depressed and got carried away after few drinks. I would convince myself if it was 1 time mistake. But what to you call when it’s been done repeatedly and fully planned. I don’t know what to do. Help please.