I was just about to post what NJ says. have you got anyone social or medical who supports you and LT because of his autism? I am thinking when you are feeling calm, it might be a good idea to have a word with someone "official" who is on your son's and your side as it were, or ast least neutral so that if the poo hits the fan and dad gets difficult, you will have planted your flag so to speak. Write a diary of latenesses, non arrival, requests refused and so on and keep it up to date, save texts and so on and make a note of conversations, then when you have got it all sorted and identified who you can chat to, go to them and express concern over what his father's behaviour is doing to your son, and to you, but focus on LT. Say that you have gone to lengths to maintain the contact but its getting too much to handle and so on. Present your self as the loving and concerned Mum that you are.