I've had a few PM's from others about what I sent to the OP for advice. Here's an abbreviated version for others:
She won't end up with the kids 24/7 unless YOU do something stupid, like hiding the kids from her that you mentioned in your OP.
NEITHER of you can deny access to the children, or you'll pay the consequences in divorce court. (read lose custody or at least end up with reduced visitation rights)
Though they are incredibly expensive, you MUST talk to a lawyer immediately. Try to find one certified in Family Law / Divorce. Lawyers are like most professionals... they tend to specialize in one or two areas. You don't want a Bankruptcy lawyer handling your divorce. Show him the evidence you have of her intentions, and then LISTEN TO YOUR LAWYER on how to proceed.
From your initial description, your marraige doesn't sound like it's worth the efforts to try to salvage. I don't know if Tennessee is a "community property" state. If it is, that means in divorce court you two divide the assets (if any) and debts of the marraige. You'll establish custody and visitation rights for the children, as well as child support.
Unless your wife is a drug addict, convicted felon, registered sex offender, or is legally insane, SHE WILL get primary custody of the children. You will get rights of visitation, and be required to PAY child support until the kids reach the age of 18. You will LOSE the right to use them as dependents on your tax returns, and you will also have to PAY THE TAX on the child support you pay. That's just the way it is.... divorce sucks.
That being said, some recent divorce agreements allow "joint custody" where the two parties basically alternate custody each week, and NO child support changes hands. If you get a really good lawyer, you MIGHT be able to negotiate this option... though it's normally done where the parties are still friendly and willing to accept this arrangement. If your wife wants to fight, you'll end up with the "standard" arrangement I described in the preceding paragraph... and you'll both end up with HUGE legal fees.
Finally, things can get REALLY ugly. You and your wife will argue over the most stupid things (who gets the photographs, for instance). My lawyer had some really good advice... in the end, it's just stuff. The main thing you should be concerned about is your children. Try as hard as you can to make it painless for them (which is impossible, but try). Don't fight in front of the kids. Don't bad mouth each other to the children when the other is not around.
If you didn't have kids, you could just divorce, part ways and never see each other again. BECAUSE YOU HAVE KIDS, you'll be involved (to an extent) with each other for the rest of your lives. The sooner the two of you both realize this, the better.
The less complicated the divorce, the less money you BOTH pay to the lawyers. If you can both come to terms with how you want to divide things and how you want to set up custody of the kids, you'll BOTH save a lot of money. I know couples who spent more than $100,000 in legal fees for divorce battles that went on for more than a year.
It's hard not seeing my child every day... but you get used to it. When we were married my ex- and I were fighting all the time, mainly about money. Life is better now though. My ex- and I make better friends than spouses. I spend my money as I wish, and I have much more fun in life. I look better, and I feel better.
If you need more advice, or just need to "vent" drop me a message. Good luck.