Ruby, we are almost 6 years past finding out that my husband had cheated on me. His was much worse - it was physical and started while we were engaged and continued past our 3rd anniversary, through the pregnancies and births of our two younger boys (we each already had a child from before marriage). Mostly one woman but others here and there as well. At the time my little boys were an infant and 2, and our older kids were both 8. At the time, we had two mortgages because our old house hadn't been sold yet. It wasn't easy, but financially it was impossible for us to split at the time and even if it had been possible, I wasn't ready to walk away from our marriage. Not yet, not without a fight.
Since then, I went to individual therapy for about a year just to have a safe place to vent. He has seen a handful of individual therapists (not just for this, he has had a mood disorder for many years) and we have seen maybe 5 couples counselors and a family therapist. I read a lot of books. Distracted myself with hobbies and volunteer commitments. Took up running, biking and swimming. It all helped. We are better - not the same, not perfect, not sunshine and roses and rainbows every day but we're solid.
This will change your marriage forever but it can make it stronger in the end. You have learned that your husband is vulnerable and has weakness in him. We all do - that's what makes us human. His imperfection has been laid bare before you. Now he has to gain back not only your trust but your respect and his own dignity. You will figure out through this where your lines are. What you can accept and what you can't. What you can forgive and what you can't. You will know yourself better because you are being tested. No matter what you do, stay or separate, it will be hard. So you will learn how strong you are (and that may be much stronger than you think). It's hard work but it can be done.
So when does it get better? There are lots of books and websites out there that outline the steps and time line (After the Affair is particularly helpful). For me, the crying stopped in about a week (like you, I told only a couple of close friends - to this day my family doesn't know anything). We went out on a date and tried to re-connect physically after about a month but that was kind of traumatic. It was about a year before things went back to normal in the bedroom. It was probably another year before I stopped having a visceral reaction to cheating (movies, TV shows, songs would literally make me get a sick feeling in my stomach). Now I can watch The Good Wife without wanting to cry. Probably another year before I considered really forgiving him. I still haven't said the words "I forgive you" but in my heart, it really doesn't upset me anymore. It happened, and it's over. I haven't checked his phone or e-mail in a long time. At one point my husband said "honestly if I had any idea how much this would have wrecked you and our marriage and how long it would take to move forward I wouldn't have cheated because it so wasn't worth it. I really thought that when I got caught you would just get over it. I really didn't think you'd care that much."
I read a stat years ago that in the aftermath of an affair, about 1/3 of couples split immediately, 1/3 stay together for 3-5 years and another 1/3 stay together longer than that. So yes, plenty of couples stay together. You will feel better. You will immerse yourself in the functions of day to day living. Bring the kids to school. Cry. Do some laundry. Sniffle. Vacuum. Read about affairs on the web. Pick the kids up from school. Slap on your happy face and stifle your emotions for the rest of the day. Put the kids to bed. Cry in the shower and then got to bed and not sleep well. Hate your husband. Hate HER. Plot revenge. Cry some more. Lather, rinse repeat. Then one day you'll forget to cry. Or you'll unplug from the internet and go for a run instead. Or be so busy running errands you don't obsess about it all day. Your husband will do something funny and you'll laugh because you forgot for a second that you're so angry. Or you'll wake up after actually sleeping all night. You just move forward - before you know it, you'll be busy with Halloween costumes and Thanksgiving plans and holiday shopping. Life goes on and you will too.