If it's any consolation, as someone who missed the window to do it when she could (lawyer got sick and didn't get me the separation contract until he and OW1 broke up, then he wouldn't play ball), I think it is the right decision to protect the finances. Resolving the finances (whether through separation/divorce/etc) is the legal split and it doesn't have to be a forever thing. You get to decide when to have the emotional split. They don't have to be together. You seem like an "ifer" at this point. Like there is a certain set of circumstances where you could conceivably reinvest, but it changes moment-to-moment. Very reasonable and understandable position.
Don't feel bad about the mean streak. Grief is complex and anger comes in waves. Sometimes I feel compassion, other times rage, but more and more often, nothing. It is why I try not to think about the good or bad things about him or what he has done. If I think about the kids, I tend to get very angry. I'm a big girl. I've learned a lot of things about myself that I couldn't in that relationship. I am grateful to him for that.
