What is the difference between 怕，害怕 and 恐怕
The context in which I would use 恐怕 is something similar to "I'm worried this  might be the case". I'd say it is used to describe a predicition or extrapolation, sometimes can be translated to be just "probably".


這池恐怕有三公尺深 :　 The pool here is probably 3 meter deep (and that worries me)
我恐怕會被留校 : I guess I'm going to be in detention


怕 alone can be translated to "be afraid of":


我怕蛇 : I am afriad of snakes
我怕高 : I am afraid of height


... or "be weak against / be bad at"


我怕燙 : I'm weak against hot (food/drink)
我怕冷 : I'm weak against cold (weather)


... or "being a chicken and not willing to face it".

害怕 is more of a mental state and perhaps less of a verb. If it is, it's probably a intranstive verb.


我對這裡的交通感到害怕 : I feel scared by the traffic here
這電影院令人害怕 : The movie theather make me scared


The use of "害" usually implies "bad effect".

Now... there could be use cases in which 害怕 and 恐怕 are shortend to be just 怕. In this sense, perhaps 怕 is more abstract than the other two. In summary:


區別的方法只怕很難說明 : Describing how to disambiguate is probably going to be difficult.


:-)