YES!! Before you confront. Speak to a lawyer. Do it today. The more you know of your rights and what would happen in a divorce, the less fear you will have. The more choices you will have.
Also, before you confront:
1: Print out the entire chat between WS and OP. Make copies. Stash in more than one location. Make a digital copy too.
2. Check the computer for emails, forward them to yourself to more than one email account. One of your accounts should be a new one.
3. Check computer for downloaded photos.
4. Check the phone bill.
5. Check your WS's phone. Looking for emails, texts and chat applications.
6. Check your credit card statements and bank accounts.
7. Get multiple copies of everything.
Once you confront, your WS will do what all waywards do... he/she will immediately start destroying all evidence so you will not know the extent of his activities.
Once you have a good idea of what the extent of your WS's betrayal has been, think about whether you want to stay married or not.
If you decide to R: Sounds like your WS had the AP in your home and probably in your bed, can you continue living there? Does the AP work with your WS? If so can he change jobs?
If you decide to D: Don't confront. Serve him/her papers tomorrow morning during his rendezvous with the AP.
I am so sorry you are going through this ascian. But it is very, very important to not confront until you have investigated thoroughly. I think there are many of us who confronted too soon, committed to R, WS destroyed or hid evidence but then are brains start to piece together the fact that there is more.
At that point, it is very overwhelming. We have lost our opportunity to dump our wayward with the most profound effect (with surprise), have committed time to rebuilding and are now caught in a situation where we have invested so much we feel compelled to keep go downing that route.
EVERYONE will tell you not to make a decision for 6 months, so you can decide when you are emotionally calmer. But I think what is more important is to investigate and get all info up front so you know what you are going to try and heal from.
Also, do not feel compelled to confront before tomorrow morning. Call in sick. Stick next to your WS. He/She will be forced to cancel his date with AP. That will buy you more time. In fact, tell him you want to spend the whole day with him. See how he reacts.
Good luck.
ETA: Do not tell the BS of the AP until you are ready to confront your own WS. Then tell the BS just moments before you confront so our WS and the AP do not have time to make up a story together
[This message edited by Jospehine85 at 1:13 PM, August 13th (Tuesday)]