Well first there's the expectation of others that you do what you're "supposed" to. Whether it's your dad, a stranger on the street, or anywhere in between, everyone has assumptions about how others should act. If what they want and what you want are at odds then it's a choice. You can do what makes them happy, or do what makes you happy. If you pick the latter, do your best not to beat yourself up about it or let others do it for you. If you pick the former then you're a martyr. Your life, your call. That's my view at least. And it's really not that easy in practice, but that's the theory I stick to :p
Personally, my dad passed before I realized I'm trans. Were he alive I'd still be doing this, no matter how much it hurt him/pissed him off/whatever. We had a very complicated love/hate relationship. There's nobody who's done anywhere near the damage to me he did, but I still love him. When he died I felt like the only person in the world who even came close to understanding me was gone. I'm not sure what your views on the afterlife are, but I look at it like this : If he's still out there somewhere he's either enlightened, in which case he'd be cool with it, or he's not, in which case he can go **** himself.
And regarding a song triggering you...music is the language of emotion, some mostly cerebral forms of music aside. I personally won't listen to Sarah McLachlan - Angel or GooGoo Dolls - Iris unless I want to feel sickeningly sad. I'll physically fight someone before I let them play that in a car I'm in. Because it's going to screw me up for weeks probably and every time I end up in that hole...well, I try not to let myself fall in.
So yeah, avoid music you know is going to have that sort of effect on you, and if it happens anyway then...I dunno, whatever kind of non-harmful coping methods you've got. Like posting here!
