1.) I understand how you would be worried about a credit score, but really? get over it. September 11th hit and my H and I lost over $500,000 in 1 week while the stock market was closed. We THEN- additionally- lost the house, the car, a job.... and a credit rating. Get over it. You can live without an 800 rating.
2.) Depending on your state, you may or may not get spousal. Only you can answer if you should go for it. You need to check your state. I make more than H, but in the end he won't get much spousal because I pay all the children's monthly sporting costs, school trips, health insurance, etc and have for 10 years. So that is deducted from my monthly income and brings it down to just about his.
3) It also depends on your potential to earn money. My H's income will increase each year, and he can make more money by taking on extra duty- which he does. If you have 50/50 custody, there's usually no child support- just agreements on who and how doctor's bills, insurance, etc would be paid for the kids.
4) I could also have written your W's letter. In fact, I think the last one I wrote H was almost the same exact thing (although I was kicking him out, and not the one leaving). Can you get her back? Sure. Do you want her back? Think on that. It's trickier than it seems. She says she wasn't happy and walled herself off. That's a loss of emotional trust. Which in turn, she perceives, caused you unhappiness. Have you earned back that trust? It doesn't sound like it in her letter. She's telling you basically the same thing I have told my H..... "I can't live with you. I am happier living apart from you. Us being together day after day, changes me for the worse, and I'm not happy". She said she noticed the changes, but still wants to move on-- she doesn't trust the changes or you yet.
5) How would I handle it? Sell the house, split the money. Divide the assets and debts; split the banking accounts (if any), sep. the titles on the cars (if needed). Get on my own insurance, and then keep DBing if I wanted him back still.
6) H and I separated for 3 years, he moved back in. 3 years later, I'm ready to call it quits again and have D papers ready. I spend almost every day wondering why I worked so hard to save my marriage to a person who never changed, and who I don't think any intentions of changing. I keep thinking I wouldn't be miserable now if I had just gotten the D before.
