My son is obese and I am so responsible

Hi , my little boy who is 6 and has autism is very overweight . We have had to buy him age 10-11 elasticacted school trousers. I feel awful , I know he has such an issue with food and that he only eats a handful of things but most are the wrong things, he hasn't really wanted do much through the holidays, he has been swimming a few times and just explodes if things don't go his way. I feel exhausted all the time and to be honest I give in to him very easy. I know all the things I should do , for one not buy the pigging stuff. (Crisps and chocolate biscuits) .

i suppose I just wondered if anyone who had been through the same and could give me any strategies that they had used to help their children.

I feel like a complete failure as a mum , I'm supposed to be giving him the best in life instead I'm turning him into an overweight little boy who will probably end up with health problems if I don't handle it now. His waist measures 31 inches , which shocked the hell out of me.

sorry for going on and Thankyou for reading