What can I do to get my child support lowered? - 2

Right now my ex wife is getting $650 a month for our two kids. She has taken me to court to try and get it raised but was denied since my income is so low (I am self-employed so I determine my own salary). My business owns my house so I have no mortgage and she was unable to take it in the divorce. She is currently living in a 2 bedroom apartment. Since she won't give me the kids and her income is so low (she works full time but for minimum wage) she is basically living month to month.

I know it sounds like I'm a bad parent but I gave my ex two options:
(1) She takes the kids and I see to it that she gets minimal support which I have done
(2) The kids come and live with me and they will have everything they need and then some
She made her choice so I'm not the one being selfish

Anyway, I want to take my girlfriend on a cruise down south since she is in college and her school year is almost over. Her and I have been together for 8 months so it is really important to me. I cannot classify it as a business trip since it is more leisure than business so the business cannot pay for it. I am wondering if there is a legal way I could get my child support lowered. Thanks for your help!

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