IB I am never sure when people post [including me] whether they are venting, journaling reflectively or looking for some sort of input . . . All are good reasons to post
I don't think there is a 'right' or 'good' time for MLC. In my case my xh was older and my youngest was nearly nineteen. And I am a fair bit older than you, so little or no chance to really recoup financially. But i don't think in most cases it is really the material things [OK with a ton of debt it is very very hard] but what they represent. The trashing of our hopes and expectations.
Your h was out the door and divorced quickly. It is all still very raw for you. And you have the OW being paraded around like a prize goat. Ouch!!
I had a very tough few years with my youngest son, with him doing extremely risky and stupid things. He seems largely through that,[I hope] 6 years down the line, but I am fairly sure that his behaviour was driven by misery at the loss of his father. In fact he is now aware of this.
Like yours, my youngest had a near miss with death. It didn't cause an overnight change, but it gradually woke him up to the fact that life was good and he actually wanted to live it.
It is like walking through fog at present, and all we can do is to keep walking. Sometimes round in circles, but eventually our fog clears, and life is better. I can't say it will happen overnight, but given your courage and resilience you will get there sooner rather than later.
In some ways it is difficult that you have to see so much of your xh. Mine largely disappeared, and I see him very very rarely. In fact i will probably never see him again now we are divorced. [That process took years . . . ] My children do not want him in their lives, except on the periphery, and that largely because he is their father and they remember someone very different from who he is now [he seems to be the only one oblivious to the fact that thee changes he has made have not appeared to improve him in any way - he thinks it is because he is no longer trying to please everyone. Hmmm that was largely in his mind from my perspective].
I wish we could go and have a large coffee or drink somewhere. Virtual is good, but sometimes proximity is needed. hugs