It would be unfair for me to tell you what to do. You need to take responsibility for the choice you make since you have to live with it, not me. The same holds true for your parents. It might give them comfort to have you married but you’re the one who will be living your life with this man, not them.
I can tell you this: Your reasons for not wanting to go through with the wedding are not crazy or selfish or unreasonable. You are a 29 years young, single, financially stable woman who has managed to raise her son in spite of hard times with his father. I hope you give yourself lots of credit. Yes, your son will miss his adult friend if your fiance drops out of his life but you’ve always been there for him and he knows that.
You didn’t mention love or intimacy or even friendship once in your letter. Although arranged marriages can and often do work in many cultures, both people need to accept the same values and be committed to the project for love to grow. You and your fiance somehow never worked through the principles by which you will guide your family. Unless you can do that, you will always be in conflict. Since you haven’t done it already, my guess is that the two of you are pessimistic about the outcome of any discussion.
You and your fiance have some hard talking to do. Try to imagine how your married life is likely to be 5 years from now. If it’s not a pleasant picture for both of you, you have your answer.
I wish you both well.