Context: the boy has just died while saving a girl and is now in the afterlife.
「……あの女の子は。……俺が突き飛ばした女の子は、生きてますか？」" 大切な事だった。 俺の人生で、 最初にして最後 の見せ場だったのだ。 命懸けで助けに入って、結局間に合わなかったのだとしたら悔し過ぎる"
It has been translated as:
That girl … the one I pushed out of the way. Is she alive ?” That was important to me. It was the first - and last cool thing I’d done in my life. If it turned out I’d been too late, that I hadn’t saved her - that would be awful.
Could you explain what 最初にして最後 means ? If if translate with my own words, does it mean: "I was a good actor from beginning to end" I'm not sure .