Sounds like stress reactions, the disassociation that you describe. Sounds like, those around you are dismissive. Having unarticulated feelings, does not necessarily make for a mood disorder. Being reactive, doesn't necessarily make for a mood disorder. What happened, when you turned 12?
Sounds like a lot of stress, dropped on you at once. Having nightmares is indicative of not getting enough sleep. Do you keep a dream journal, for analysis? Tapping into your subconscious, can clarify, feelings in your conscious mind.
Fyi, your ex sounds like a player and real jerk.
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