Starting over.

This is a throwaway account to protect a whole bunch of stuff, but here is the long story.

Met my wife when she was in high school and got married right after she graduated. I'm two years older than her. Her first infidelity was her giving a hand-job to a friend of her family's. This was a few months before we got married and at the time I was sort of a fundie christian and believed that just being an awesome husband and father could give her reason not to cheat.
Spoiler, this didn't work. For the last seven years she's been running around on me. I've not know the whole story, often finding out after a few have occurred. She has slept with close relatives, friends, co-workers (of hers and mine). Recently I found out that actually had an affair a few years ago with a guy from her old church and he got her pregnant, so my third child isn't actually mine (he's two years old now now), but I have adopted him as my own. After this news came out we tried to do counselling for the first time.
She saw her own counsellor, I saw my own, and we met with a marriage counsellor.

Little did I know that she had actually started hooking up with a guy from her work. He got her pregnant as well, but she got an abortion since the guy didn't want to take care of the kid. I found out about all this and she fed me a story about how she didn't care about him at all, but it just so happens that I saw her type her password into her phone, and this morning I took it and mined everything off of it (I'm a programmer by trade so writing a script to do this wasn't mega difficult.) and there I found that she had actually been continuing to talk to this guy and make comments about how much she wanted him and how much she couldn't wait to be with him, etc.

This was actually after she gave me an account of all that she claimed had happened, but the texts revealed a lot more than she was letting on and she has shifted her story several times (how many times they had sex, where, when it started, did they ever practice safe sex, etc)

I consider myself a great husband as do most who have met me and seen me with my family. I have never been unfaithful to her, I take care of my kids and love them, I'm great around the house (I pretty much do all the chores and maintain everything), I have a great job that pays pretty well (I'm making around 75k a year, which isn't amazing, but nothing to scoff at either.), I'm also never violent (I prefer to resolve conflicts with words, haven't been in a physical altercation since probably kindergarten).

I love her with all my heart and I love all my kids (the third being counted amount them as far as I'm concerned), but this kind of turmoil in my life is crazy. So far I have been able to prevent my work from knowing about all of this by keeping a stiff upper lip and kicking ass at everything.

From my conversation with her today, she would be all for an uncontested divorce, making me the primary caretaker of the kids. I don't want to try and take her kids away because she actually is a great mom and they love her. I also can't afford the $1200 dollar minimum fee for a lawyer.
I can't do a contest divorce financially (I'm up to my ears in student loan debt).

My questions to you Reddit.

Do any of you know of a relationship coming back from this? (I think I know the answer, but would be good to hear of others experiences)

My job could take me anywhere, and a dream I had was to take my kids to other countries to experience things I never got a chance to as a kid, if I divorce my wife and don't fight for sole custody of the kids, does that dream die?

How do I start over? I'm tearing up writing this. It's the simplest question, but also the most complicated. I've been with this woman since I was seventeen.
She's the only person I've ever made love to and she's been my only friend for a while. I'm very reclusive so I don't meet a lot of people.
It's hard doing this all by myself.

Also. I have a little girl. I want her to grow up and not be what my wife was (she doesn't know about anything that has happened.
We've kept it pretty together with our kids.) How do I facilitate this, how do I learn how to raise a girl? I can braid hair, but it's pretty bad, and I have no sense of fashion so any time I dress her she looks pretty bad.

If you have any questions, please ask and I will answer.

tl;dr Wife has spent our whole marriage being unfaithful. I have three kids, and don't know where to go from here.