you said you understand all the reasonings, but you can't help youself.
for some people, once they undertand the rationale, once they convince themselves, they can pull out, detach, and move on, relatively easier, they think with their heads, not their hearts, but some people will not be able to do that, until they are very much hurt.
i hope you are the first type, who can move on easily, and if you are the second type, hope you manage to move on before you get too deeply hurt, or to let the situation out of control, or somebody get hurt (in every way).
time will help, but reading, talking to a good friend, or a psychologist may help (not the HK psychologist guy, but an independent third party).
meanwhile, if you want to think independently, you have to detach first from those complicated situation.
good luck.