It is gonna sound cheesy, but what got me into my current mindset regarding it was a quote from the recent Elton John biopic. When Elton was struggling with the identity crisis and trying to articulate the mismatch of who he was vs. where he saw himself being in the future, one of the characters told him "You got to kill the person you were born to be in order to become the person you want to be".
For myself personally, I concluded that we are simply who we are at any given moment. There is no "real me", there is only "me" at a point of time (given that I act genuinely, of course). If I act differently after drinking alcohol? That is still me. If I undersleep and act cranky for the rest of the day? That is still me. If taking the meds is what it takes to kill off the parts of me that I was born with that impede the current me, then so be it.
I realize that it is a really reductionist mindset not comprehensively describing the reality, but it helps me to come to terms with myself and somewhat describes the situation as I perceive it.
I definitely prefer the new me. There is a continual spectrum of mes from being a young kid to an adult (ship of theseus style[1]) but this is different (and I think Elton John's situation was similar). I can clearly see a me I like and an alternative me. In theory, every day of my life I make a choice to give that day to the me I like - but gods when I think about it it can get heart wrenching. Digging in, I'm basically denying that alternative me a chance to be alive... And I've never killed that other me, it's sitting there and I might be that me tomorrow, it's just that every day so far I've chosen that today won't be the day it is me... Similarly Elton John could always return to being Reginald (or however he identifies his older identity) he just doesn't.
As someone who waxes philosophically this is an interesting consideration to dive into but thankfully most days I skip right past it and don't perseverate. It's pleasant to share though, since I don't like vocalizing it with most folks.
The way I see it, it isn't really "killing", as in, getting it to not exist at all anymore. That old "you" will always be there, just like a bunch of other possible "yous". The "killing off" part means getting to a point where going back to that old "you" becomes as difficult as it was for you to get to the current "you" from your old "you".
And I totally feel you on the part about thinking too hard about it. This outlook I have is definitely not comprehensive and just provides satisfaction at a cursory glance when my mind wanders there. Looking at it under a microscopic view, there are individual parts that can be deconstructed and found to be not super accurate. But overall, it seems to provide me with a good enough framework to look at my life through.
What are your goals? Was the "old" you getting any closer to your goals? Is the "new" you getting closer? It's OK to take the pragmatic view of your environment and situation in life. These things matter too, especially when you have to support a family.
It's quite the dilemma really.
Oh man, sure, the medication makes me a better member of society... but am I killing the old me? Am I discriminating against the old me? In taking the medication are we declaring the me I was born as a dysfunctional useless person?
I actually came to pretty much the same conclusion, I prefer being the me that is clear headed - the medication is a requisite for that and I dislike that chemical requirement, but I prefer this me.
I think I've gotten more over this after bringing someone bipolar(with some other issues) closely into my family, they are drastically different when off balance and constantly have to fight (adjusting meds, checking Li levels) to stay on balance... And the off-balance person isn't a bad person, but they're highly internally inconsistent, they constantly put roadblocks in their way and, even when the meds are way off balance - they'll come through stable for random moments and strongly want to rebalance themselves.
Their condition is rough enough that they can't self-correct, I can mostly self-correct, it's hard but if I've run out of meds I can make it into the Doctor and get more and I feel quite lucky to be able to do that.