When are you planning to begin school? You can’t fill out FAFSA until October 1 if you plan to start in the fall of 2019. If you are starting fall 2018, you fill out the currently available FAFSA and you use your 2016 tax returns. That means the support he sends you now is not relevant.
In response to another poster who asked the same question (but it was her parents who had the recent divorce), this is what @kelsmom said: