for what it is worth. there is only one really bad situation inderwater. that is out of air. if you have air you can survive. given that when you loose the mask stop, breath untill stable, close eyes if needed, become calm , determine your problem and then think of he solution for your problem, and then preceed with recovery. the worst part of any problem is the transition from all is ok to the all is not optimal. NOT UNMANAGEABLE BUT not perfect.
lost mask , you got air no problem
lost fins, you got air no problem
got tangled, you got air no problem
seperatered from your buddy, you got air no problem
you have to believe this: and... the only time you should become stressed is when time is working against you, if IF YOU HAVE AIR YOU HAVE TIME.
it is premature to adress the obvious question at this point of your training. one step at a time.