I feel guilty at the same time because i am the reason his family hates him right now and they even let the elders know.
He chose to start a relationship with you, a non-JW. As a JW, he knew full well the consequences of a 'worldly' relationship. You are not the reason for his problems.
He is 29 but acting as a child, continuing to allow his family to control every step of his life that he doesn't keep hidden from them. It appears to be acceptable to him that his sister took access to his phone and read through his private messages. And it is now acceptable to him to break off with you because his family found out and told him to break-it-off?
If you can't contact him, does that mean they placed him on a type of 'curfew' and he lost his phone privileges?
You both are adults but act like children who must meet in secret and do everything his mommy and daddy require. Your understanding and easy acceptance of this situation has not helped the relationship.
When a couple is truly in love, almost nothing can separate them. There seems to be no indication that he has fought to keep his relationship with you but he (and you) appears to have accepted breaking-off with little or no effort to keep it alive.
In entering the relationship with your eyes open and accepting the unusual conditions required, how long did you realistically expect the relationship would last?