and a shovel
Personally, i would recommend that this is the straw that breaks the camel's back for you. It is utterly ridiculous that you are not allowed to ask/plan for DS visits. he is 2 FGS, he needs to have things prepared for him.
TELL XH that he needs to be responsible for DS shoes too, and that if he is not prepared to give you the money, then he can take his DS to Clarks and get them replaced. No argument.
Put it in an email, so that you have proof if you need to, and then you can start compiling evidence that he is being deliberately combative and difficult.
He replies badly, you have proof. He shouts at you in person?, reply again by email saying I was disappointed that you felt it necessary to shout (and then insert all the crap he's spewed at you) and should this verbal abuse continue, that you will seek legal advice and transfer all contact to via a contact centre as you are concerned for the welfare of your son.
Seriously, you are out of that relationship, he has no right to tell you how to do a thing, he has no right to order you about, or to make you play guessing games, and certainly he has no right to wilfully ruin your DS clothes and not replace them.
don't give him access if he is behaving this irrationally. Remember YOU actually have all the power. If this toe-rag stops paying maintenance, you can go to the CSA, you can get help and advice.
he has no right to hold you and your DS to ransom.
was he always this abusive?
If DV was an issue, you need to contact Woman's Aid and get yourself onto the Freedom Programme.