As some others have implied in their posts, whether the JWs are a cult and whether you are bitter are two different things, though certainly connected. But even if you are bitter, that doesn't mean the JWs can't be a cult.
In fact, I would point out that the fact people are so enmeshed and can't really distinguish themselves as their own person is one of the indicators that it is a cult. This is why we call it the Borg, after the Star Trek race that assimilates people into one big machine hive-mind. In a healthy relationship with a group, the person is autonomous and at the same time part of a united group. This is also why there is disfellowshipping, if one was not so dependent on the group it would be a joke, or atleast nowhere near as devastating as it is. Also taken into consideration the whole "no part of the world" stuff where they essentially shuns everyone that's not a JW, (so that you can't be part of another group and get support from them) you got a pretty clear picture of whats going on. This whole set of circumstances fosters an immature psychology dependent on the group.