Give yourself credit, you are in a hard situation and emotions are normal. Its ok to feel overwhelmed, just try to walk away from the kitten and take a moment to take care of yourself. Be patient with him and don't expect too much from him as he is still young and scared, and don't expect too much from yourself at first as you are still grieving. If it happens again remember that its ok to walk away and give both of you a moment to calm down. It's a big adjustment for both of you, take it one day at a time and know that it's OK to give each other space. You both have the love to give each other but it will take time for both of you.