この道に前に進むしかない・（これに決めた以上）最後までやり抜くしかない

1.I'm in trouble now. I shouldn't have gone out in the woods by myself, but there's no turning back
now. The only thing I can do is to find my way back.

2.She knew she should never have let him kiss her. Now there was no turning back.

3.After he hit the bully, he knew there was no turning back - he would have to fight him!