His Other Wife by Deborah Bedford

Hilary and her son have survived a divorce and now he is graduating from high school. Eric, Seth's father, has remarried. Eric and Pam and the two children are coming to Seth's graduation and expect Hilary to entertain them in a "happy" family setting. Hilary finds she is still very angry and Seth's anger is surfacing, the strain on both evident in their actions. When a high school graduation party backfires, Seth is in trouble and Hilary is feeling guilty and alone. Bedford writes a convincing tale of blended families and the obstacles that need to be overcome.