In that moment, Richie was forgetting the obvious, that Uncle Ray, Aunt Barbara, Andrew, and Melinda all love him and he clearly loves all of them back!
His brother and sister arrive at exactly the right moment to prevent him from choosing a permanent solution to a temporary problem. Richie has been so overwhelmed by his mother's illness and subsequent death, plus the added drama of his father's inexplicable behavior that he was only seeing the pain and suffering he had to deal with. Compounding his trauma was one of the few things that brought him joy was snatched from his life abruptly.
Sometimes we are so close to our problems that we can't look past them to see the wonderful things that are occurring just a short distance away. Giving Richie a little space and time away from his sperm donor will hopefully allow Richie to see things from a different perspective. The sperm donor needs to explain himself and he and Richie need to listen to each other more respectfully, maybe with a neutral observer to moderate things.