As such, trust in the law for protection is not an effective option. I understand that building a strong community can be helpful(as I believe this is one of the many forms of security that can be increased with the help of friendship), but what else can I and other people do to deal with anger, resentment, and especially anxiety in scenarios like this? What would Epicurus and his followers advise?
SillyApe
I am sorry to hear all that which you posted. You have raised all sorts of issues which are impossible to deal with directly without more details, but you are also right that it would probably not be appropriate for us to try to go further into details which are no doubt very specific to circumstances.
I definitely think however that what you have raised can lead to generally helpful discussion of how to analyze any situation.
And it seems to me that if you truly have reached a stage where "trust in the law for protection is not an effective option" then your first priority must be to do what you can to secure the safety of yourself and your friends. Whether that requires what Kalosyni mentions of moving to another area is too fact-specific to say, but I personally not would not approach what you are describing as primarily a therapy issue, once you make sure that you avoid being out of control (which I gather is a concern per this comment:
When I read this, my blood began to boil as never before. I started shaking with anger.
So long as you do not let anger or any other emotion make you act irrationally, I would seek to use the anger as a spur to taking appropriate action. There are references in the fragments to Philodemus stating that Epicurus held some types of anger to be appropriate. In fact the last thing i would do would be to prioritize "calming down" over taking firm action, if firm action is in fact required. In recent podcasts we've seen Cicero take the Peripatetics to task for too loose a willingness to compromise with certain types of strong emotion, but with Epicurus the focus is always on the result, not that there is a magic quantity (zero or any other quantity) which is always bad or always good.
Epicurus left not one but two locations under terms from which we might infer that he was not welcome in those locations, so yes Epicurean philosophy will offer advice on keeping anger under control, but remember also that Epicurus says that the wise man will feel his emotions more deeply than others, and this will not be a hindrance to his wisdom.
No doubt PDO6 is relevant, and there are other references that make the same point that safety is an extremely high priority.
PD06. In order that men might not fear one another, there was a natural benefit to be had from government and kingship, provided that they are able to bring about this result. PD06: The translation given is by Mensch. Formerly we used Eugene O’Connor from “The Essential Epicurus": "Whatever you can provide yourself with to secure protection from men is a natural good.” Bailey: “To secure protection from men anything is a natural good by which you may be able to attain this end.” New Greek Version: “In order to obtain security from other people, there was (always) the natural good of sovereignty and kingship, through which (someone) once could have accomplished this.” This version is up for review given that the Greek for sovereignty and kingship clearly appears in the text but is emended out by Usener and others. See the discussion of PD06 for further detail.
Also there is PD14. The most unalloyed source of protection from men, which is secured to some extent by a certain force of expulsion, is in fact the immunity which results from a quiet life, and retirement from the world.
PD39. The man who has best ordered the element of disquiet arising from external circumstances has made those things that he could akin to himself, and the rest at least not alien; but with all to which he could not do even this, he has refrained from mixing, and has expelled from his life all which it was of advantage to treat thus.
PD40. As many as possess the power to procure complete immunity from their neighbors, these also live most pleasantly with one another, since they have the most certain pledge of security, and, after they have enjoyed the fullest intimacy, they do not lament the previous departure of a dead friend, as though he were to be pitied.