I called the ambulance because I was pretending to have a heart attack
Why would you joke about such a serious event?
I wanted to fool my uncle to make him leave before my mom got there.
It is a crime to fake an illness and take resources away from people in trouble. You should confront him and ask him to leave, if he won't call the police.
I can't do that. I will feel like a loser if I fail in this. I have to make him leave.
If an ambulance comes then you're going to get stuck with the bill. Ambulance trips are expensive and may put you into debt. You're better off just asking you uncle to leave instead of ruining your credit by accumulating debt over a poorly thought out plan.