Your a year or two older than me, I know how the starting over again is one hella intimidating facet.
I'm glad your son is aware, and checking up on you. That's a great bond to have. At least you can be open to him, he's been thru this before with your first wife. And he's old enough to understand how "life" adds its twists and turns.
I understand how right now your thinking "leaving isn't a bad thing, wonder if I really did love her". That's your own way of putting up those defenses to protect yourself. Tomorrow or next week you might be right back to "damn I miss her, and hope this will work out". That's why they call it the roller coaster. Enjoy the ride, and understand your gonna be on it for a while, nothing wrong with that, your only human. You are going to be making excuses for yourself to feel one way or the other. Just know its going to take some time. One way or the other.
I meant to ask, just to clarify your much ealier post. Your S8 is going to be living with you when she moves out? If so, do you have some help with him? For those times that you need a break? At the same time, trying to be there for him, is so hard, its important as he's going to be going thru his own issues as your wife probably hasn't been much of a mother to him lately. She's running. This is the one part you need to truly separate your feelings of betrayal and not get him involved. Just be the best damn dad you can!!! Don't hold it against your wife in any way/shape/form. Those are regrets you DONT want to have later, but are the easiest to pile on now.
Allow yourself to grieve a bit, heck, theres nothing wrong with just sitting down and needing a damn good cry to let out some built up emotions. Don't keep it bottled in. When my father passed away a long time ago, then a sister, I had to be the man, I didn't cry. I don't know if its the testosterone depletion that starts at our age or what. This hurt all hurt 10x worse. Maybe cause there just isn't the same finality of it all. We have to rehash it for so much longer.
Its so hard to not think in absolutes, or not put a time frame on things one way or the other. Just let it go, understand where you are, try to set some small goals for yourself that you can reach, and build on some positives. Know that its going to take some time to pull yourself out of the funk, you might not be having some of your best work days, and allow yourself to forgive yourself for that. Don't rush the process, its going to take what it takes, just know you'll get there.
Things I did to keep myself busy, and try some new things: Golfing, cooking classes, took a few dance lessons, went to the library and sat and read there to get out of the house (also good for u cause they ususally have a great kids section/play area). Spend some time with a few friends, got out of town to visit some family (also a good idea with holidays coming up). Took some guitar lessons. Really focused on being there for my kids, one has her own place, my youngest lives with me (almost done with high school). The cooking classes were a great meet place, I was usually the only man in the class. I was even passed a phone number in one of them by a much younger, single woman. I remember how flattered I was at the time.
I think the hardest part was the friends thing, I didn't really have any friends left in the area. Not those kind of friends anyways. So just getting out and trying new things was more the key, meeting some new people. I started doing that almost immediately. Even when I didn't feel like it, I got out. You need to too.
Hope you keep posting, its another way of not keeping it bottled up. Did you get a copy of Divorce Remedy yet? See if one is at the library? Maybe start a journal at home?