Nervous to have sex..

Okay so i've had sex before and im not scared of it or anything but now i'm with this guys who i have been in love with basically my whole life. i've dreamed about having sex with him so many times but when it comes to it i just can't do it. he makes me soo nervous even when we just kiss i start to ramble on and on and then when things start to get hot i back out the moment something could happen. any advice on what to do ?? i know its crazy😂