1.First I would start of with telling her that she is deserving of all the love

1.First I would start of with telling her that she is deserving of all the love and respect in the world. Show yourself your selfworth. If he is not capable of showing respect, show yourself and your children you are worthy. 
As for telling the children, I am a firm believer that it is very important to inform them because it can be very easy to get confused as a child as many up and downs, back and forth happen between adults in this moment. Children deserve to know the truth of the matter because it is also their life that is changing entirely but also taking into consideration their age and mantal capacity.A healthy relationship with your ex can help the children process their emotions of all the unknowns of the changes to come. Open communication on changes that are happening can help them easily navigate through daily concerns, emotions and any fears they may be facing. Always showing a united front is key in communicating things about the matter to children, this way both parents know what is being said. Also, allow children to be honest with how they feel at any moment. As a parent one must be minful at the fact that the children have lost their home as they knew and a parent in their daily lives. Children will always need both parents in their lives and keeping them as priorty is first and for most. 
2. Going through a divorce, especially when infidelity is involved, can be a harrowing and stressful time in one’s life. You are right to wonder how much to share with your children. Research emphasizes prioritizing children’s needs during divorce, providing security, stability, and open communication (Amato, 2009). While honesty is essential, tailor the information to their age and maturity. As Dr. Judith Wallerstein, a renowned divorce researcher, suggests, “focusing on the broader issues that led to the divorce, such as ‘a lack of love’ or ‘constant fighting'” can be a helpful approach (Wallerstein, 2003, p. 42). This explanation is truthful without burdening them with adult concerns.
Most importantly, create a safe space for questions and reassurance. Let them know you love them dearly and that the divorce is not their fault. Consider seeking professional guidance from a therapist specializing in divorce to help your children adjust and maintain healthy relationships with both parents (Amato, 2009). Remember, many families navigate divorce, and resources are available to support you through this challenging transition.
While going through my divorce from my daughter’s father some years ago, one important thing that our family and divorce therapist taught us was to never talk down about or on the other parent, especially in front of the children, as this can cause problems with the child during the divorce to swing one direction or the other and this is fair to nobody especially the child (Emery, 2015). They should never feel like they have to choose sides. Remember, this divorce is between you and your spouses, and the children should never get involved with the messy, grave details.
Remember, you are not alone. Many families go through divorce, and resources are available to help you navigate this challenging transition. Here are some resources that you might find helpful:
The American Psychological Association: https://www.apa.org/topics/divorce-child-custody
The National Healthy Marriage Resource Center: http://www.healthymarriageinfo.org/research-policy/marriage-facts-and-research/
With time, understanding, and the right resources, you and your children can adjust to this new chapter in your lives.
I wish you all the best,
Leslie (The Advice Columnist)
QUESTION FOR THE CLASS AND PROFESSOR KRISTIN:
Divorce often disrupts family dynamics. How can Lady in Distress (I decided not to give her a name for anonymity) encourage and support her children in maintaining healthy relationships with both her and their father despite the marital breakdown?