Porn addiction /cheating

Am I wrong I’m currently 21week pregnant with our second child.and just recently found out that my fiancé of 2years had a porn addiction. He just recently admitted it to me when I found out with our bank statement and I then went through his phone

And waited to see if he would tell me

He been paying for zoom calls from only fans

$100-$200 to watch them live to have sex

Just him and the other two people a women and guy while he watches on this call

Would you think this is cheating.

He waits till me and our son are alseep to do this

Every 1 month 3-4 week he will do this.

Do you this this is cheating

Because I do in some form of way

He calls it porn

How do we move form here do I leave do I stay?

He wants me to help him he think it’s an addiction