Onlyfans Tax Return Custody

I was notified that i will be receiving a very large Tax return for the income i earned while doing OF for about a year. During that time i was with a boyfriend who helped take pictures, and manage a social media account to promote. the OF account was owned by me alone, was under my email, and the money was sent to my account strictly. We had a verbal agreement that i would send him 45% of the earnings while the account was active, which looking back was too much for someone who never appeared in the content itself. but since it was his idea and he’s the one who got us followers in the first place he convinced me he deserved at least half at first which i shot down. we’ve been broken up for 6 months now

Basically; he is demanding he receive 45% of this tax return money, an amount that would be well over $1500. he is threatening legal action and telling my family i did OF if i do not agree. what im really wondering is if he has any legal entitlement to this money. the account has since been deleted (i still have all the emails i received during its time) and the accounts HE used to promote it have also been deleted.