What happens if I can't help myself?

Mary • Hi! I`m Mary and I`m a college student. Been with PCOS for 17 years. I like volunteering and playing with my phone.
I have a particular guy friend in mind. I'm in love with him, but I'm afraid that if one of us pushes boundaries such as touching private places while making out or something, that I won't be able to help myself. Clothes will come off and you know what will happen after that. Any advice to break or stay far away from sexual tension like that? I really hope I'll be strong enough to say no. If not I'll feel so bad afterwords and won't have anything to give to my future husband virginty wise. Please help!