Catholic student in long distance engagement

Hello everyone, so I'm having a bit of an existential crisis. I'm recently engaged and also just got accepted to nursing school 4 hrs away. My FI and I already live 7 hrs away from each other, so we had considered moving in together where I'll be attending school because a) we've been apart for a while and we won't be getting married until almost two yrs from now and b) I'm not allowed to work in my program so he'd be helping me with expenses in order to not use as much in loans. I'm totally for it, but I have a very conservative Catholic family and I don't know how to tell them without being told I'm "living in sin". Another issue is that I've heard of many priests who refuse to marry couples that are cohabiting, but I also wouldn't want to start off my marriage by lying to my priest. Any advice?