Type 1 diabetes

Hi, I just started dating this guy who has type 1 diabetes and am looking for where to get information on it. His sugar dropped so low today and wouldn't go back up and it scared me so much especially bc I didn't know what to do or really what the numbers are supposed to be. There is so much information if I just google it I wasn't sure if anyone has any sites about the basics of type 1 and insulin and such so I am more prepared next time. TIA