Being helpful/supportive versus being yourself

I feel like there's a natural tension between those two things. Or rather, sometimes I'm in the mood to be altruistic and self sacrificing and sometimes I'm just in it for myself: for entertainment, for gratification, for attention, etc., and I really don't give a ###$ about anyone else.

I realize that this is an identity issue but I'm curious...

Do other pw/BPD struggle between being a basically good, conscientious person and being basically selfish, almost antisocial even?

Does anyone else feel like they have multiple (even conflicting) "selves"?

How do you negotiate a balance between the two? Which impulse holds sway in any given situation? Is there a difference between whIch of the two motivates you in the short term versus the long term? Do you look back on impulsive actions and wish you had acted differently? Which do you think is the "real you", the flawed, selfish one or the idealistic one, and why?

I am a very helpful/supportive person, that is my real self. I really like to help people, but if I recocgnize someone is trying to exploit me, I get really angry. I am not altruistic.
Before becoming really sick due to BPD and comorbid diseases, I was very helpful also to people around me but who were not so close (relatively, since I do not have many people really close to me), but my new way of living is to now really think deeply whom I help in which situation, because sometimes I costs a lot of energy and at the moment I need my energy for myself.
It was a somehow long process for me to become a little bit more egoistic, but I feel it helps me. And I feel good about me. Of course there are also people for whom I would do everything at every time, but I am more selective now.

I'm not supportive, and I don't want to be. I often don't care about the satisfaction and needs of others. Why struggle between personalities when you can just act accordingly?