Found Out My Wife Has Been Having A Affair For Two Years In April.
She Stopped Seeing The Guy She Claims But Gone All Secret Again. I Think She Got A Pay As You Go Sim But Don't Know The Number But Know His. Is There Any Way I Can Get A Copy Of His Phone Bill On Orange To See If They Are Still In Contact

As you aren't the account holder the chance of getting a copy of his bill are ZERO mainly due to privacy laws.
It's even difficult at times to get a copy of your own bill, as you need to prove to them who you are.

If you don't even know if she got a phone, and don't even know the number there is little you can do.

If you file for divorce you can though the court ask her for the number and a copy of the bill to be provided. ( of course she cuold merely lie and say there is none)

The point at this time is that you don't have trust in her, so you have to make a chioice, do you wish to leave her, or not, if you want to leave her, do so. If you wish to stay, get marriage counseling.

She stopped after she got caught? Whoa boy I would have been gone. Just me though.