Getting super nervous flying over ocean.

Hi Everyone, i recently started flying after 11 years break due to my fear of flying, my first flight was only for 2 hours and now have booked a 4 hour flight gradually making my way.

I will be flying 2 hours over ocean which is making me super nervous and thinking about cancelling the flight, can some one please walk me past this darkness and throw some light on how things work, i have an idea about Etops, but my mind keeps asking what if it needs immediate landing and am not able to counter that.

and How do pilots manage to do this every time and super scared please help.