Ex-wife frequently harassing for added extras despite getting $1,500 child support per month - TEXAS

State of Texas: My husband's ex-wife is the custodial parent, she has the children 54% of the time, my husband and I have them the rest of the time. She gets $1,500 child support every month, the payment has never been missed/never been late. That amount was set down by my husband's divorce lawyer which the judge agreed was right, based on my husband's high earnings.

She is making a frequent habit of doing things like texting us at 1am, harassing us and nagging about how she thinks we should be paying her more. Never a hello, a please, or a thank you, just bitchy, bossy-boots demands.

Where do we stand legally with trying to stop this? She seems to have it in her head that she can tap us for as much extra money as she fancies, when she fancies it, and that we are the unreasonable and neglectful ones for not just handing it over.

We also got some moronic abusive texts from her new boyfriend in the middle of the night telling us that ''$1,500 a month is not enough''. Apparently they are not in love and do not share a bedroom, he is just some kind of roomate that has moved into the old marital home to help her with her rent. She works a minimum wage type job yet lives in a 4 bedroom house.

Any advice on how we should try to nip this in the bud? Or some piece of info/law about why this is wrong and needs to stop? Thank you.