I guess the best thing to do is shift your mindset. as opposed to thinking of it in terms of "killing their daughter" think of it more like... a caterpillar turning into a butterfly. sure it's different, but it's not bad, you'd simply be growing into who you are. also making the choice not to transition could lead to adverse mental health that may also lead to the death of their daughter. ultimately transitioning is a personal journey and it's about your mental health.