Majority of people enter marriages planning on it to be forever.
It’s not healthy for children to grow up in dysfunctional home. No matter how much you are into their mother. Her daily presence is detrimental to your children. They’d benefit from therapy and Al alon.
I’d refrain from telling your children how much you miss her or how you wished your marriage was different. It’s not right. They aren’t your marriage therapists. If you two were together and she went on business trip is one thing, but she left and lives elsewhere and there’s talk about divorce. You shouldn’t be sharing how much you miss her. It puts them in a very bad role. Any therapist would tell you that. They aren’t third party in your marriage. What’s happening between you and her isn’t something they need to be involved in. Yes your son becomes quiet and distant because that’s just not right.
Yes it’s hard. But you need to find a therapist or a friend to discuss your wife and marriage.