It's always hard, but it's the same as submitting any research to a journal. You are always going to get corrections, some which you take on board, and others you disagree with. It can seem overwhelming and there's been many a time I've looked at my comments and just thought 'there is no point, I'm clearly not good enough', but that's not the right attitude. Give yourself a few days after feedback (my ego was always bruised) and then tackle it bit by bit. Minor changes first, so you see you've accomplished something. Then itemize the major changes and working through them a step at a time. You're not alone, everyone hates feedback, and sometimes anything less than 'you're amazing' can feel liek the end fo the world. Just take your time and keep going