Need advice

I'm an RN, working in LTC. Started a new job a month ago, and have unfortunately found the facility management to be very unprofessional. Being new to the nursing home environment (after having worked in a doctors office the last 4 years since I became an RN), I received 3 days of orientation. In this time, I had very little actually training, as my preceptor was an LPN who has only been at the facility herself for a couple of months. Despite this, after a month of mostly figuring it out on my own or asking questions of my co-workers when I could not, I experienced a horrible shift last evening that now has me questioning whether or not to even return to work on my next scheduled shift tomorrow evening. I work on a skilled nursing hall where we typically have 20 patients per nurse (3 of us on 3-11 shift) with 4 CNAs total. So last night, halfway through the shift one of my fellow nurses became very ill and left to go to the ER. Our unit manager was made aware and after calling around with no success on a replacement, told the remaining two of us to split the hall (giving us 30 patients each) for the remaining 4 hours. Despite this, where the shift went wrong for me is thankfully not patient related. Instead, as I walked out of a patient room (at the end of the hall, where I had just set a patient up an iv pump, given an injection, a nebulizer treatment, and oral meds), I was blind sighted by the Facility Director, who came towards me yelling about how the phone had been ringing for 20 minutes (he was calling) and saying someone should have answered it. (There is no receptionist at the facility after 430pm on M-F or all day on weekends/holidays) Without giving me a chance to even respond, he stormed out of the facility. While I certainly understand his point, I do feel that his behavior was completely unprofessional. (There were patient's families visiting and several CNAs in the hall during his outburst). How should I approach him regarding this issue?