How would you handle this info?????? Please advise!

I was off work 10/30 and 10/31 (2nd shift). A nurse has recently come back to work after her husband committed suicide a few months ago. I went to school w/ her and she has always been a party hard kind of person...loves to drink and pop pills and smoke pot. Ok....well..when I went back to work on 11/1 the other nurse that had worked with her on halloween said that this nurse left early both the 30th and 31st...about 9pm....to go drink. She came in on halloween with a huge hangover and was bragging about it..then disappeared for over 2 hours...turns out she was in an empty bed ASLEEP. She worked my unit. Last night on 11/1 one of my pts told me "I never got my eye drops last night." and I asked her if she was sure. She said "yes Im sure. You always give me my drops." and so I said ..'well..maybe you've run out let me look and see.." so I open up my cart and there they are ..both of her eye drops over half way full so she definitely wasnt out. I then told her "well. I dont know what to tell you. I wasnt here so I have no way of knowing if you got them or you didnt other than what you're telling me. " but I believe her b/c she is oriented x 3. So then comes shift change and Im looking through my narc book. I noticed that on this same pt a vicodin had been signed out for 9pm by this nurse. I go to last months records (it was changeover night on the 31st) and look to see if anything was documented about giving her this vicodin....nothing was there...nothing was on the mar, it wasnt signed out on the mar and it wasnt documented anywhere in the chart, on the report sheet or on the pain flow record. I think this nurse was not only hung over...but I think she might have taken that vicodin for herself. I didnt get a chance to finish looking but I plan to go through it all with a fine tooth comb tonight when I work and see how many "prns' she actually signed out for on that narc book. It didnt even catch my attn. til I was counting off with the night nurse. The count itself was correct so thats why I didnt notice it before then. My question is this.....should I mention this to the DON? And how? I wasnt actually there so I dont want to say anything that isnt true but the nurse that told me about it is legit. She also told me that something was wrong with one of the pts on my unit and the aides couldnt find that nurse so she had to go check my pt for low bld. sugar. Once this nurse woke up from her lovely nap..she said she felt alot better and left early..again. I did leave my DON a note and stuck it under her door that she needed to check the time punches for 2nd shift on those dates but I didnt sign it or nothing. I disguised my handwriting b/c I dont want to be the one who gets someone fired. This nurse has issues, but..she also has 3 kids to feed, clothe and house. On the other hand...if you are STUPID enough to go get blistered and come to work w/ a hangover......you got no business being in this field...much less responsible for medicating anybody...of any age or condition. This nurse is only PRN...but shes always been unreliable, unpredictable, and shes always been a party girl. I couldnt believe it when she was actually hired to start with. She got fired from her last job for refusing a drug test b/c she got caught sleeping on 3rd shift and probably a few other things....and whats so de ja vu about that is that the facility she was fired from for this is the absolute worst facility in this area. i just dont know what to do with this info. I dont want to be a rat but at the same time why cant I take one freakin night off and not have to wonder if my pts are being cared for? The DON put her on a probationary period already and let her get off scott free when she made huge med errors not too long ago....we had to write up 4 big ones in one shift from her...she hung the wrong IV bags, etc etc....If I had done that I would have been written up and probably fired. What would you do?