We feel guilty when we act contrary to how we've been taught to act, even when we want to change our belief system. As children, many of us were taught to put our parents' wishes and needs far above our own. We (intellectually) know now that we have a right to put our needs and desires first now, but it's a hard pattern to break out of, so we feel guilty. Or that's my working theory, anyway.

You are breaking free and maybe your parents are trying extra hard to pull you back in. The guilt you feel is not necessarily reflecting that you are doing anything wrong--it's reflecting that you are doing something different, breaking the family patterns.