How to not be afraid of doing your back handspring?

I go to tumbling (you know gymnastics but only like floor stuff) and and when i do my back handspring on the mat with the guy spotting me, he only holds me by the edge of my shirt. so its just him like poking me or puttin a finger on me but it makes me feel safer. then when he doesn't toutch me i get so scared that i can't even jump. tryouts have been for the past 3 days for cheerleading but the official judging is tomorow and i just need to do it once but i cant get myself to. pleaseeeeeeeeee give me some tips. i've neen doing cheerleading for almost 8 years now and i really wanna make the team. thank you sooo much!