Parent problem.

Sovie , not ignoring you mate , just that this is a trikky situation . Ill speak to my wife tonight and see what she thinks .

I hate to be blunt, speaking about your mother, but the only thing I know of that can make a woman go to such extremes is great sex.
What do your brothers say about it/him?

My brothers don't really seem to have an open problem with him. Although I don't think they have seen everything I've seen. And they always have an unspoken problem with anyone my mom dates for the first few months at least.

My other siblings aren't really as close to my mom as I am. I was always the Momma's girl even though I'm not the only girl, or the youngest or anything.
The thing is now I am uncomfortable around them both, mostly him.
For all I know my mom is doing drugs, not just sitting back and watching.
This is really tearing at my mind, and I'm worried about my mom.
She has a really weak heart, has had 2 heart attacks before she even turned 40 (she's 45 now).
Over the last 5 years we have all helped my mom get back into a better state of health, and I worry that she is about to throw it all away.

I did a little research on Cocaine, and the things I learned make me worry even more. I worry for her heart and her mind.

Is this something I should just be brutally blunt about and say "mom, i know what's going on and I can't support it. I can't be around you if it's going on"? I want to but its my mom. We aren't supposed to talk to our parents like that, they should be the ones coming to us, and making us get our lives straight. I think that might be why this is so hard for me, she has turned me into the last thing I ever wanted to be ... a Parent.

Oh my!
A few things stick out in all of this. I, too, am an RN. I work at a psych hospital and have been in a lot of weird relationships. One of the main traits of nurses are that many and/or most of us are co-dependents. Its our nature. Some are aware of this and others are oblivious. Read up on it and decide for yourself. I can guess that most of your mom's relationships had major aspects of co-dependence and addiction!
Second, I disagree with the member who stated great sex as the reason. Great sex couldn't motivate such a weak emotional move this woman has made. I seriously doubt it. Most of us men are horndogs and don't need to live with a woman to want to have sex with her, no matter how great it is. I think the situation is much deeper than that. It lies in her emotionally vulnerable state. I suspect many men with issues prey on a woman like her. And with her emotional state she is all to willing to be victimized out of pity or the desire to "fix" people as their caretaker.
Then their is another glaring statement that made me think something else. Birds of a feather fly together. I suspect your mother may have been on drugs for a long time and been hiding it from you. She could be abusing all kinds of drugs. Drug abuse is common for nurses and very prevalent. I feel this about her because not only is she with a man who is a bad alcoholic and drug abuser, but, also because of her heart attacks at an early age. The precursors could certainly be cocaine and alcohol use. They seem to go hand in hand with many alcoholics. Maybe in the past you were so busy in your own life you overlooked obvious signs. Maybe she was gone a lot and had what you considered reasonable excuses. Then again, maybe she is a great hider and has used the drugs for so long that the signs of intoxication are not as noticable. A real addict over years of abuse, takes maintainance doses regularly. If this is the case with her she could be using cocaine while using the bathroom, walking to the kitchen, going to her room, walking the dog, you name it. Its very easy to use and the pro's don't need credit cards, mirrors, razors, straws, and all that other paraphenelia you saw in his car. They can simply take "bumps" all day from a little inhaler. Getting a small amount on demand.
Tread lightly on any confrontation with your mom. It could lead to alienation, conflict, and other forms of resentment. Tact in addressing this issue is essential. Good luck! I wish the best for you and yours!