Answer
In this counseling service:
Sexual relations are an Islamic right that both spouses have on each other. Therefore, the counselor advises the sister to honestly talk to the husband about her feelings and why seeking the help of a marriage counselor would be important in this situation. If after all nothing changes, the wife has the right to seek a divorce.
As-Salamu `Alaikum dear sister,
Thank you for sending us your question. I am sorry to hear about your truly difficult situation. I ask Allah (swt) to ease your pain and to end your emotional suffering.
Your situation is truly a great test. I can read in your question that you have endured a great deal of pain as if you are grieving a loss. You lost your hope for a normal and healthy relationship that includes emotional and physical intimacy. You certainly noticed that your relationship lacked these two important factors, and like any other committed person, you hoped that things would eventually change for the better.
Unfortunately, things haven’t got better. Again, as a committed person, you attempted to solve the issue by going to marital counseling which was certainly the right thing to do, but yet again, things didn’t go well. Now you don’t know what to do, and you feel like you are at a crossroads.
You have mentioned that “the quality of our relationship has caused me a great deal of resentment and depression and jealousy of other couples.” You certainly have every right to feel that way since a big piece of the puzzle is missing.
We all know that sexual relations are an Islamic right that both spouses have on each other, and marriage is the only outlet for people to experience this right. The fact that the both of you have not had sexual relations or even any kind of physical contact for over ten years can no doubt create distance and a great deal of emotional strain. Something needs to be done about this.
You also have mentioned that your husband “seems to be satisfied with our limited degree of interaction.” He may be satisfied, but you are not, and you need to communicate with him about your feelings openly and honestly. Marriage is a partnership, and both parties must practice empathy with each other in order for a relationship to succeed.
You mentioned that you and your husband went to a marital counselor and were not able to continue because he was not willing to share personal information with a third party. Is he at least willing to share his personal feelings with you? Does he know that you are feeling resentment and anger as a result of his lack of emotional and physical intimacy? If he does, then how does he react towards you?
You said that since you were married, your husband has always been distant, shy, and introverted. It certainly may be a personality type, but is there something more than that? There are a lot of unanswered questions that need to be discussed between you and your husband, and the proper form of help needs to be sought.
My advice to you would be to first attempt to connect with your husband on an emotional level no matter how little it could be. Talk to him; talk about anything at first. Talk to each other every day no matter how unimportant or trivial your conversations may be. I can understand how the last ten years have probably created a huge strain and feelings of anger in you particularly, but attempting to reconnect with your husband is certainly worth your time and energy.
After you have established some sort of connection, start talking about your feelings towards him and the quality of your relationship. Use empathy, but at the same time, you should also be open and honest about your feelings of hurt and resentment throughout these years. Attempt to have some sort of exchange of ideas about the quality of your relationship and what should be done about it. From there, I highly recommend that the both of you go through marital counseling once again. A trained individual may be able to help the both of you communicate effectively and establish some kind of common ground between the both of you. 
Of course, counseling is not effective to those who were forced to participate, but you need to communicate with your husband that counseling is very important to you and may be the only way to solve these deep rooted issues.
As for your question about whether masturbating on pornography is permissible, kindly seek help from an Islamic scholar. Ideally, you should not be put in a position to resort to pornography to satisfy your sexual needs, especially if you are married! I hope that this realization should motivate you to be diligent in finding a solution.
After you have honestly tried to solve this issue with no positive results, then, Islamically, you have the right to make a decision to either leave or stay. No one can make that decision for you since you are the only one who knows your capabilities and what you are willing to sacrifice. Whatever you choose to do, please do not believe that leaving would be “selfish.” You also need to take care of yourself in order to take care of your other responsibilities.
I ask Allah (swt) to grant you the strength and wisdom to do what is best.
Salams,
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