I agree that you need to sit down and have a very serious conversation with her. This is an illness that can be controlled, it is not easy and it will most likely be a difficult road travel, but if you love this woman and want to marry her, then you will be willing to take this path with her. Remember that vows are "in sickness and health".
This is not a way for her to live and I am sure she is not happy with it either. OCD is not an easy thing to understand, because to the outside world it is just junk, garbage, but to her it is more than that, and to get rid of it will cause anxiety that you cannot imagine. This things are tied to her compulsions and probably a superstition of sorts that if these things are thrown out something bad will happen. OCD is about control and the way we try to control things. most often things that cannot be controlled, are not always the most logical of ways. You cannot expect her to simply throw out her things, on a whim, or just because you say so, it's unfortunately not that simple. If only.
Like I mentioned earlier, this is going to be a long road, but not a hopeless one. With the right counselling, and probably the right medication, this situation can resolved.
My husband also thought I was insane, totally loopy and off the deep end. But to show that he loves and accepts me for who I am, flaws and all, he proposed to me, while I was doing what I do best, and that is cleaning. It was a very important gesture to me, because it meant that he loved me and all of me and supported me to the fullest. There are times when he cannot take me, and my second guessing or my contant need for reassurance but it's those times that he tells me that he can't and we deal with it. He supports me through therapy, medication, and washing my hands till they bleed.
This situation needs help. It will not resolve on it's own, and you can only help her so much. However, if she does not agree to get help or she does not change there is no reason to fake your own death :) Im sure that there are other alternatives.
You do have to lay it down for her, and have a very serious talk. You cannot be expected to live in a mes of junk and she shouldn't force you, nor she should be forcing herself. Have the talk. Find the therapist and a good Dr. Just remember this is not an overnight fix. Have patience.
Good luck,
Sorry for the late reply, I was away on vacation.
Why don't you sit down with her (I assume you still love her and would still want to marry her if the hording wasn't present, and perhaps the other OCD symptoms) and tell her that you cannot live your life this way and that the only way you both can get married is if she seeks professional help. Tell her you will go to the first appointment with her but that she needs to get help or the marriage is off. She can get better with the proper help. Start with a psychologist who specializes in OCD and CBT. My husband thought I was a looney toones when I first went off my own OCD cliff. I came back and while I do panic occasionally for the most part I am fine. Even this last time I nose-dived, I just said "I'm going to be a little crazy for a while but I will get better." And of course I did. You can live with this, I promise you, but she does need help. Good luck.