Welcome.
As Delilah has said the healing library is a good place to start.
I offer a few bits of advice to the newbies as I welcome them, and I tend to be pretty matter of fact in my presentation, and can come off harsh. That is not my intention, but there are a few things that are pretty cookbook about A's (affairs) and as a BS (betrayed Spouses)we need to step back and take emotion out of it, to help us make the best decision for ourselves that we can.
1. Get STD tested. It's icky, and upsetting, but it must be done. If your WS (Wayward Spouses)spouse says they used protection, chances are they didn't. Afterall at this point the one thing you can count on is that your WS is not trustworthy.
If you are struggling with the basics staying hydrated, eating and sleeping, then let your Dr know exactly what is going on, and discuss if something will help you to get through this either short term or long term. Many folks here have needed a little pharmaceutical support and there is nothing to be ashamed of in it. If you are malnourished, or sleep deprived it impairs your judgement and ability to make good decisions.
2. See a lawyer. Find out your rights, your WS's responsibilities, and how things would play out if you did D. Find out if it matters who files, all of it. Get the answers to the what if's. So then you have knowledge, and can again make decisions based on reality, and not suppositions or what if's.
3. Seriously sit down, and think about what your absolutes are if you are considering R. And if so what the consequences will be should your WS not want to go along with these. Many of us struggle initially even with WS's that are willing to attempt R, and part of that is because we as BS's are too afraid to create consequences for them. (Read the profiles of myself, and a few others that are veterans, you will see where our mistakes were, and where we made really smart moves that saved us).
4. Allow yourself time to grieve it's ok. Your M as you knew it is now dead, and as such you need to grieve. But also force yourself to take positive steps in healing yourself. Whatever that may be. IC (individual counseling), Working on self improvement to help rebuild your self esteem. Whatever. Be kind to yourself, and do one nice thing for YOU and you alone every single day. A walk, a bath, exercise, a pedicure, whatever just time to find center, and be calm.
5. Find at least one person in real life to share this with. Infidelity thrives in darkness and secrecy, and as such your WS has probably asked that you not tell anyone, or even forbid it. Too damn bad, they didn't think about you and destroying your world when they made their choices. Time to put your needs first.
6. Remember Nothing you did or did not do caused this. Your WS is broken, and needs to own that, and do the work to figure out what is broken, why it's broken, and do the work to heal it. (we call that owning and fixing your shit in these parts).
There are many here that will offer support, some may upset or offend. Take what you need and leave the rest. Read, post, and share.
(((and strength)))