<human>: Give me the gist of the text in a nutshell

We've been together for over a year, and she's lived with me for about four months. Lately, though, things have gotten really bad. We've been fighting practically every day for months now. Things reached a boiling point on Tuesday when I basically said that we're through if we don't see a couple's counselor, because things were never going to change if we don't get some help. She reluctantly agreed to go this coming Monday.

Here's the snag... she left her Facebook open today, and my curiosity got the best of me. Apparently, she's been venting about me to her ex (from three or four years back) on Facebook Messenger. This alone wouldn't bother me much, but he's been sending her pretty explicit messages. She doesn't really reciprocate, except for this one exchange that I can't get out of my head.

Him: "Whatcha doing?"
Her: "Curled up watching TV."
Him: "I wish I could be there next to you."
Her: "Me too"

She tells him later that they're not together and he should give her some space, but this whole thing still infuriates me. I don't know if she's actually cheating, but the guy is sexting her and she's *letting him*. On the other hand, I did find out about it by being a sneaky little shit.

How the hell can I handle this? Do I come clean? Bring it up at the counselor?... or is that irrelevant now? I kind of wish I could unsee that conversation... it's made a bad week a hundred times worse.
<bot>: Girlfriend and I going through an extended rough patch. We agreed to couple's counseling, but I snooped on her Facebook and discovered she's been having some intimate conversations with her ex, who clearly wants her back.