Hi, I want very much to make Aliyah and serve in the IDF, but my father and my grandparents on his side are very much against this. They guilt me constantly and say I would be abandoning my family. What should I do?

Lag Ba'omer 5770 It is a well know gemara that when a parent's wishes contradict the Torah, one is obligated to listen to the torah and not to the parent.. As the Gemara (Baba Metzia 32a) says: From where do we know that if his father said to him, ‘Defile yourself’, or ‘Do not return it’, he must disobey him? Because it is written, "Each man should fear his mother, and his father, and keep my Sabbaths: I am the Lord your God— you are all bound to honor Me. Since Aliya to Eretz Yisrael is a mitzvah which is incumbent upon every Jew in every generation (רמב"ן תוספת לספר המצוות מצוות עשה ד, פתחי תשובה לאבן העזר סי' ע"ה, ס"ק ו)) your parents can not tell you not to fulfill this mitzvah. The issue of the conflict of the mitzvah of honoring one's parents and Aliya to Eretz Yisrael was already dealt with by the earliest Askenazi Rishonim as the Maharam of Rottenberg (שו"ת מהרם מרוטנברג שער ב' , סימן כ"ח, סי' ע"ט) whose decision was that the mitzvah of aliya to Eretz yisrael overrides the mitzvah of honoring one's parents. [Much literature in English can be found in the newly translated and published book "Rise from the Dust", from pg. 150 and onward, written by the Kadosh Tzvi Glatt Hy"d expected to reach the bookstores within a few weeks.] Cotemporary poskim upheld this decision such as Rav Ovadya Yoseph Shlit"a (יחווה דעת ח"ד סי' מ"ט) as well as Rav Shaul Yisrael zt"l (עמוד הימיני סי' כ)) and Rav Natan Tzvi Friedman zt"l (מח"ס נצר מטעי, RavChaim David Halevi zt"l, (שו"ת עשה לך רב חלק א סימן יח)). However, Rav Yisraeli z"l stipulated that this is not the case where the child is responsible for the caring of his parents and Rav Friedman zt" said that the intention of the child must truly be to fulfill the mitzvah of living in Eretz Yisrael and not for the purpose of getting away from his or her parents. In addition, you are most probably aware that being away from parents can cause them anguish and hardship. Since you probably would like them to be with you on this major decision in your life, my suggestion would be, in addition to this answer, to find a Rabbi in person to whom they can also speak to and get the assurances any parent would want for their child so that you can alleviate the period of hardship for them. This way you can also already begin to pave the road for your parent's Aliya as well.