You should immediately see a psychiatrist so that you and others can be protected as well as the storm in your mind be calmed. It is good that people like you are coming forward to protect others. Yet, it would be wise to first become stable and resolve your own problems before trying to help others. I am 28 and my girlfriend is 20. A few days back, we had sex and she was unable to describe her feelings.
Sex is an expression of two people showing the closeness of relationship they share.
Unfortunately, a large number of people of all age groups get stuck on sex. They forget to show their affection and love in others ways. If you focus on how you could come closer, it would automatically be enjoyable. There are no scales to measure sexual performance and what is pleasurable for both is perfect for them as a couple.