Hi, I'd like to help you with your problem.
It sounds as if your wife is going through some sexual issues as well as some feelings about her relationship with you. She is unwilling to see a therapist since she already is one and possibly doesn't feel it would help.
In dealing with her sexual issues, I highly recommend she see her doctor. There may be a hormonal imbalance that is causing the dryness and lack of interest in sex. That is an important first step to either establish or eliminate a physical cause. Is she willing to take small steps in addressing this issue? You could try taking it slow and going out somewhere special first. Then after a time, move to kissing. Then to caressing. Try each step until her comfort level builds. If her issue is physical, then this will not work until she can get help from her doctor. But if it's emotional, try this and work on the emotional issues as well.
Whether or not she has a physical cause to her lack of interest in sex, there also seems to be some emotional issues for her in your marriage. Whenever you have a partner that pushes the other away, it most likely has to do with hurt feelings. Somewhere in the marriage, she started to feel either rejected or hurt by something that occurred or even over time. It could also have to do with her past relationships and some of her experiences from those could be interfering with your marriage.
Since she is unwilling to talk with a therapist (which I still recommend, if you can get her to go. Even therapists need help solving their own problems), you will need to work on this issue together. First, you can tell her you are willing to work on this issue with her. Then spend time together talking about how each of you feels. Give each other a set amount of time to express whatever you feel without the other partner saying anything. Use "I" statements only. No personal attacks.
There is a website called http://www.5lovelanguages.com/ that can help you learn how to communicate with your wife better. Also, there is a DVD available that you could try called "Making Marriage Work" by Dr. John Gottman. Also, if your wife is unwilling to see a counselor, maybe she would be willing to talk with her pastor, if she attends church. The main focus here is to understand what she is feeling unhappy about and working together to give you both what you need out of the marriage.
I hope this has helped you,