I have a Patreon with a 50/50 split anonymous partner, and we're not incorporated. I send him half of our income - where do I report that in Self-Employed?

Every month I send him half of our income via PayPal. He's in a different country and wants to remain anonymous and we make a hefty amount of money, so I'm worried about paying taxes on the whole amount and not just my half. How do I enter payments using Self-Employed? If that's not the right software, what should I be using?