You didn't do anything wrong, love.
It was quite useful for me to find out my XH booked a prostitute on AW just 6 weeks into seeing his new girlfriend. I suppose although I knew it wasn't my fault there was a 0.0000001% of me that still didn't know that.
This is not about you, it's about him.
You know my view:
- he won't change, he'll do it again
But even if you thought he could change:
- you'll have a shit life because you'll be wondering and trying to go through his phone and degrading yourself stalking him because you'll never be sure (it's just not worth it, there are lovely men out there, plus single is better than that!)
But now you tell us he got you to suck his cock last night 

- what kind of grade A arsehole responds to the situation that his partner knows he is cheating, by wanting sex - and very much a "for him" sexual act.
He really doesn't think very much of you, does he? 
Google the "pick me" dance. FGS don't lower yourself to giving him blow jobs in competition with prostitutes 
There is nowhere for this relationship to go when you know you can't even tell him to show you his adultwork account.
There are women on here who have come back from affairs, and the constant theme is HONESTY.
This isn't an affair though, it's prostitution. And as I said upthread that's s cold hearted calculated act and I don't think you can come back from that.
What kind of man expects sex from you when he should be BEGGING you to stay with him? He knows you're feeling too weak to end it. He thinks already that he just has to weather the storm and minimise it - because the minute you didn't end it instantly, as soon as you listened to his shit, he knew he was home and dry. And thought he'd get a nice blow job 
Time to tell the bastard you're actually not pathetically desperate to keep him, and he can go pay to get his cock sucked, and not come back.