I would recommend using a DBT skill: DEAR MAN
The following is an example of DEAR MAN loosely based on a failing relationship.
D (describe the situation) I have noticed that we have been growing more and more apart. We don't talk often and when we do it's impersonal. We rarely touch and intimacy is almost never. When I do reach out to you I don't feel like you want me to. I see it affecting the kids. Their grades/behavior/friends has changed.
E (express how you feel about it) I miss it. I miss you. It makes me feel sad and lonely when we don't connect. When I reach out to you and you aren't receptive, it makes me feel unwanted and alone. I feel worried about the kids and their happiness and I feel it's largely because we are not providing a good foundation of love in our home.
A: (assert your wishes) I would like to work on rebuilding what we had. I want "us" back. I want you to feel wanted, cherished, celebrated, important, and I want those things for me too. I love you and I hope you still love me. I want the kids to grow up in one home with two happy parents.
R: (reinforce why this is a good idea) I know we would feel more united if we spent some time remembering why we got together in [insert year] and I really want to work towards that.
M: (stay mindful - stay on topic) Keep your emotions in check. Don't raise your voice. Don't argue, don't get angry. If she gets defensive, acknowledge her pain and return it to the points of what you want going forward. Don't diminish, but don't argue. Say you're sorry for your part and you want to do better.
A: (Appear Confident) Don't stammer, don't beg, don't grovel. You have put great thought into what you want to say and you know it's what you think is best. If you appear wishy-washy, you are less likely to be taken seriously.
N: (Negotiate) If she isn't interested at this time, bring up some ideas on how you want to hear her out. Offer her some time to think about it. Tell her you will table the discussion until [set reasonable time - two days away perhaps] and would like to discuss some more.
*** these skills work in ANY negotiation in which you have a goal. Using this template can be used in many situations in which the potential for emotions/arguing to escalate is there. Staying focused on the goal and not the extra crap is difficult and this DEAR MAN is very useful for those kids of situations ***