Is true spiritual fulfillment possible only by getting rid of all worldly possessions and relationships? Is there a middle ground where I can attain attain spiritual fulfillment without total lose of ego?
It’s fine for a spiritual aspirant to have worldly possessions and relationships. The important thing is that his or her happiness not depend on wealth, possessions, relationships, fame, power, etc.
Many great saints have possessed great wealth, but it did not touch them. Think of the ancient King Janaka, for example. In more modern times, Paramhansa Yogananda’s foremost disciple, James Lynn, was both a liberated master and a self-made multimillionaire; he was not attached to his wealth, and that was the key.
As for your other question, there are degrees of spiritual fulfillment: The ultimate spiritual fulfillment comes only with complete dissolution of the ego (“ego” being the sense of being the body and personality, rather than the soul). However, on the path toward egolessness, our happiness, freedom, and fulfillment increase with every step—and thank goodness, else how many people would ever walk that path?