I don't think anyone has called you lazy or a scrounger, but if they have then it will be one post in amongst ten pages, so not worth getting upset about.
I don't really think it makes much difference that you ex was a twat or that you are out if work through no fault of your own. Those are the circumstances you are in unfortunately, and they are the reasons why you are struggling financially. Not your DHs ex.
It may be your opinion that the school coat should come out of the maintenance money, but that's not your call to make so you just have to suck it up.
You might have a point about the gift each month, as I said earlier in the thread, but that is between your husband and his ex. Your husband won't buy the gift if he doesn't want to. People can't just demand things from other people's bank accounts. Clearly your husband does want to buy these things, so why aren't you annoyed at him instead of the ex?
And no, the ex refusing to pay half the cost of her son going on holiday with his dad doesn't give you the right to moan about that. If your husband was paying for his other two children and contributing to yours and getting to enjoy the holiday with his son, then it should be him that pays. I wouldn't dream of taking money off my ex so that I could take our children on holiday with my new husband.