Ex’s cash income and child support

Hey all, seems like this is the place to ask. 2 kids, 50/50 care with the ex. My ex quit their job and started a cleaning business middle of last year. The last financial year they only earnt $34k apparently, while renting a house that would be $600 a week odd. I earned $55k, but work for a NGO so with salary sacrifice, grossed up to $69k.

The CS yearly review has me due to pay around $250 a fortnight to the ex which is totally fun with my kids money and would pretty much end any chance of me having any fun myself.

Ex has recently been overseas to visit family, apparently flights paid by current sucker, and car bought for them by parents apparently.

Anyone have similar experience and some guidance for me to try?