Jaime,
I am so sorry this happened to you. Welcome to the best club no one ever wanted to join.
There are a few things you can do right now, since you’re in such early days.
1) get tested for STDs. Make him get tested, and make him show you the results (not tell you.)
2) make sure to eat. If you have no appetite, try protein shakes or power bars. Stay hydrated and get as much exercise you can, it will make you feel better and help you sleep. Low intensity exercise lowers cortisol, so just a long walk will help.
3) talk to a doctor if you need sleeping aids, or anti-anxiety / anti-depression medications.
4) talk to a lawyer. This is just for informational purposes at this point. Just to know what your rights are, to know what a divorce might look like. Having the information will remove one source of uncertainty, and that alone is worth the consultation. Many law firms do the first consultation for free.
5) get a therapist - one who specializes in betrayal trauma
6) he needs to get a therapist too. He may have a sex addiction.
7) eschew marriage counseling at this point.
8) ask him for a written timeline detailing all of his infidelity. Who what when where etc. When he’s done, you can ask him to take a polygraph to prove to you that he’s being honest.
9) you don’t have to do this alone. You can talk to a close friend, or a sibling, or a parent. They will support you - just ask yourself, wouldn’t you do the same if the situation was reversed? You have nothing to be embarrassed about, though that is one of the most common reactions. Totally normal, but believe me, the shame is his, not yours.
It’s so early. Just know that you will survive this, and we are here for you.