how can someone say 7,5 years into the marriage that "you are my perfect soul mate, I want to grow old with you" and half a year later, "we don't fit, we should have never married"?
It'll take a while to come to terms with things, but people change. Particularly when they realize that the majority of their life decisions have been made based on bad assumptions (i.e. the cult is true). Your wife has been living under the thumb of an oppressive cult and is now free and is probably rethinking everything that she thought she knew. Unfortunately it seems she's come to the conclusion that your marriage was something that she realized she wasn't happy with too. That's hard to take, but it happens to the best of us sometimes.
The key thing to focus on, I think, is that you now have a level of freedom to direct your own life that you've never had before. You're the boss, you control where your life goes from here. Take advantage of that and start doing the things you've been putting off for one reason or another. Start working to make your life look like you want it to look. It's painful to feel as though years of work have been wiped out, but starting from a clean slate can be liberating, too. Just because your marriage didn't last forever doesn't mean it was all bad or that it wasn't worthwhile. You had some happy times and you learned some things - the outcome doesn't invalidate that.
Give yourself time to get over it, but don't accept excuses from yourself to wallow in misery longer than necessary. Keep making progress. Keep challenging negative thoughts - for example when you think "I'll never be able to move on" stop for a moment and see if that's really true - you've got many years ahead of you and there are many examples of people moving on from this very situation - why should you be any different? Remember to take good care of yourself as well and find ways to reduce your stress. Divorce is typically considered to be the second most stressful event someone can experience (second to death of a spouse) so you're going to be dealing with a lot. Assemble your support system and rely on them to get you through. It's not selfish to ask things of people during this time, most people love having a chance to help the ones they care about so you're really giving them an opportunity that they will cherish. If your support is a little thin from your departure from the cult, then I would suggest talking to a therapist (especially if you have EAP through your job, if now's not the time to use it, I don't know when you would) or find a support group for people in a similar situation. If nothing else, you're doing a good thing by coming here to vent.
You will get through this, people manage to do it all the time. We're all pulling for ya.