It was not whining in any way. Just so we're very clear. You are stressed to the max, and tired. I can see that. But that's when we tend to lose our path, progress and frankly control. I just wanted to give you a nudge back in that direction, because you are not the kind of person something like this beats down. You are the kind of person who will survive, strive and then thrive after this.
May is right, anger is good, especially in keeping you safe. So just to clear things up again. I'm not say wooosahh your way to spiritual enlightenment, because you are beyond anger. I'm just saying, be angry for the things that H took from you. Like you're concept of self. Or the ability to sit down and relax for one GD second. Or the how he's taken absolutely no consideration for his children in this. But don't waste that precious little energy you have left trying to end this chapter and start the next being angry about things that you can't fix (like the future relationships of your stepsons) or about things you probable should accept a tiny bit of blame for (like expectations.)
H is a piece of work, and is putting you through the ringer. You deserve your anger. Just don't get twisted in details, or wander off into silly corners that are a waste of your mental and emotional energy to dig your way out of. Get angry and things that deserve that kind of emotional labor.
Next if you read through, which I know you have, a lot of LBWs are not timid little mouse women, who were scooped up by they're high school sweetheart before they had time to really get to figure out who they were and by the time they started to figure it out their husband ditched them with 3 kids for a younger version of themselves. Most of us are really bright, and really self possessed, and really should've known better or done better or picked better. But we didn't.
Everyone who goes through this goes though the kind of existential crisis you're facing. Who am I if this could happen? Who am I if this is my life now? Who am I if I allowed WAS/WS do these things to me? Why did I take this for so long? Why aren't I good enough? Why aren't I enough? How could I let myself end up here? Why didn't I know better? On and on. You have had your life ripped out from under you. You are in the ugly part of a novel where there's just a blank page and then it says "Part III: Post Divorce- Starting Fresh; Chapter 12...."There's a reason they skip over this part. One because it's boring, no one wants to read about painting walls, and packing boxes, checking in with attorneys and stagnant legal processes. The other part is this is just a little too much character development in too short of a period of time to be believable.
You are who you've always been. And you are the person you've always wanted to become. When you're sitting in that anger of yours thinking about all that stbxh has taken from you, focus in on the parts of yourself that were robbed or compromised to keep him happy, to keep him quiet, to keep him off your back, or just general to keep him. Think about all the times you've been happiest in your life. Who were you then? What about her do you miss? Think about all the things you've always wanted to be or do and have had to put on the back burned because it didn't fit into your old life, or the old version of yourself. H may have taken a lot from you, but he didn't take who you are at your core and he didn't take your future.