Bigy - Good to see you posting. I think that one of the toughest things for many of us to deal with is the fact that we have no control over the events going on around us. We are merely spectators of someone else's performance.
I would strongly recommend not contacting her new guy. Her agenda and his are not yours.
As far as your children's reactions to the new guy goes, again, that's out of your control as well.
In my case I am a big believer in honour and duty as well. But knowing where that path lies is difficult some times. Your sons, like mine have a duty to love their mother regardless of her actions. In the case where this guy or some other one at some indeterminate time in the future becomes a permanent part of her life and by extension their's, they will need to treat him with respect regardless of their opinions of the circumstances.
For my own son and daughter, they continue to have a relationship with their mother that I have nothing to do with. One of the big frustrations for me was the fact that there was so much secrecy and by extension lies that they got from their mother. To me that shows a lack of respect for them, but the truth has always been so very important to me and less so to my kid's mother. I have no idea what they know or if they've met her guy or not. She's been seeing him for over 2 years now so I would certainly hope so - but again - I don't know. It's none of my business even though, like you, we are still legally married.
Part of what we are taught here is "detachment". I think that I'm pretty well there. We all struggle with it. You maybe want to take a hard look at what you are feeling. I still get those feelings from time to time and label them jealousy.
After playing the field and "finding herself", perhaps there is a chance that she will turn back towards you. The known safe place. There are no guarantees. Your duty is no longer to her. You do still have a duty to your kids, yourself, and your community to be the best man that you possibly can be and to be an example of decency and honour.
On BD H52, W50 T27, M26 S21, D23 BD-9-Mar-16 D-15-Jan-18 Final-19-Apr-18 I am a storyteller. The story may do you no good. But a story is never for the listener. It is always for the one who tells