I go through the same thing. It is a completely valid feeling and fear. A few things to remember are that you cannot control the things that happen. Anything can happen at anytime and yes that is a very scary thought but you have to remember you can not control that. Also another thing is having the person your worried about do frequent check ins (a simple txt even if it’s just an emoji or something, or a quick Snapchat)

anxiety and panic are difficult to deal with for me too. I've done so much practice with breathing exercises that i almost do them automatically, and it really helps to do that at the beginning of a panic attack. if you can come up with a mantra or phrase to say over and over, like i use "everything is okay, i will get though this" that might help you get through the panic. if you cant control it, sometimes anxiety medication can help if it's really bad