Ok, I guess I'm just back to gripe some more.

I took the advice all of you offered and did have a frank discussion with my NM after my original post. Turns out there had been complaints from other nurses that follow my RN as well as pt complaints. So she was given a small slap on the wrist and actually did improve for a couple of weeks. But then she quickly eased back into her old habits.
One day this weekend, I came in at 1100 as usual. There were 5 pts in ER. My RN had gotten a LPN and an aid from the floor to help her since floor census was low. We never have that much help. Usually its just the two of us, so you'd expect exceptional care with this type of staffing.
One of the pts had been dropped off by EMS before I got to work, but no one had been in with her when I got there. So I spent the 1st hour or so with her as she was covered in urine and feces and needed a good scrubbing in addition to all of the other things such as IV, telemetry, etc.
So when I finished up, I asked the other LPN what else we had going on. She proceeded to give me report starting with a pt she was very concerned with. Pt had a recent colon resection, c/o abd pain, pale, and some mental status change. "There's just something wrong with her" per the other LPN. She tells me she had told Nurse X that something is wrong with the pt several times and Nurse X just says "okay" and doesn't check on pt. Pt was in CT at the time I was being told this.
Pt returns to room and I'm in to check on her. Pt is very pale, cold, and diaphoretic. Lethargic with slurred speech. Abd very distended and tender to touch. Bright red drng from rectum. BP 58/36, pulse 104. This pt was brought to the ER at 0930 and this is what I find at approx 1230!!! BP was low on admission; granted, not this low, but low. In the 3 hours she was there, no line started, no additional VS taken. Nothing had been done for her except pain meds administered once.
I get pt into Trendelenburg and rush out to get IV tray. Nurse X asks me what I'm working on and I tell her pt is going bad, suspect massive GI bleed/perforation. She says "okay" and goes back to her pt with conjunctivitis!!!! Not once from the time I saw the pt at 1230 until I transferred her out, did the RN come into that room.
I did discuss this with the shift supervisor as soon as I had this pt safe and secure in an ambulance. And I showed her the chart so she would see for herself nothing had been done for this pt in 3 hours. She also talked to the other LPN who backed up my story about Nurse X not going into the pt's room. The supervisor promised to discuss it with my DM, but I really expect nothing to come of it.
I don't work with Nurse X again until late in this week. But I am really dreading working with her. I am to the point that I really expect her laziness/apathy to kill someone. I can give you more examples like the one above if you need them. I really don't want her to take my license down with her. What should I do? Can I refuse to work with her because I feel my license is jeporadized and because I don't want to see someone die just because she doesn't want to be bothered to check on them? What are my options here? Any advice is greatly appreciated. And if I'm being overly critical, I'd like to get that feedback too so I'll know if I just need to chill out.