Having experienced many other people's infidelity-driven divorces I must add my voice to the "Get A Lawyer" chorus.
People are some of the most horrible things on the planet. It's true. People you loved, cherished, and adored can turn on you like rabid animals. She'll turn it all around in her mind so she can rationalize her infidelity through demonizing you.
That's just human nature ... when we do something despicable, we demonize and blame the other party. And, to run contrary to the fellow that preached finding out if she's just pushing you away or some such ... I'd distinctly suggest against that.
She'll most likely try to turn the situation back on you, get you to blame yourself, and try to draw you back into the whole mess. She'll say she loved you, but you ignored her, and she sought solace, yadda yadda. Maybe blame a bad childhood, an inattentive father, whatever.
When it gets down to it, America is a culture of excuses, and we need to be accountable for our own actions. We won't be until people start holding us accountable. ... Does it really matter if she felt "ignored" or "didn't get enough attention"? It was her responsibility as your wife and parter to communicate that successfully and work it out instead of indulging her baser instincts and jumping into bed with another guy.
That, as Phoam mentioned, is a character flaw that she'll probably keep forever. And, I'm sure, it'll probably carry down. A friend of mine is going through a divorce with a woman that cheated on him ... and she's currently using a niece they had guardianship of as a weapon, telling the little 3 year old that "daddy doesn't want to see you today" and scheduling visitation on weekends she knows he'll have to work, and basically attempting to hurt HIM for the percieved slight that "led" to her infidelity. And using a child. It is, frankly, disgusting, but she's able to rationalize it all away in her mind.
It's probably safest to say to yourself that A) You didn't know her. and B) As somebody you don't know, you do not know what she is capable of.
Don't sit around thinking about murder or reconciliation or finding out what went wrong. Get yourself a lawyer, keep a running log of every exchange, and keep your nose clean like clorox. She might not go after you like a rabid dog, but regardless it puts YOU on footing to make decisions for once. If YOU want to be lenient if she doesn't turn spiteful, then you're in a position to do so. If you get caught with your pants down you'll have a: "My evil ex raked me over the coals, screwed me, stole my son, and ruined my life!" story to add to the one that ended your marriage.
Be ready. Be prepared. Think of an airtight case for custody and leaving a cheater and a traitor together as all the revenge you'll ever need ... because the alternative is having this much more pain added to what you already have if they catch you unawares. Jump to the fray first, teeth bared and lawyer set to kill.
--HT