No wannabe author needs telling it is hard to find a publisher. Most give up after a few rejections. But you cannot get there if you let rejections put you down. Let's face it, times are tough in the publishing world and a mainstream publisher really only wants to take the risk of a new author if he can see big bucks. As for an agent, his 10-15% is only of your much smaller bucks, so he or she is even harder to convince.
It is therefore heartwarming to tell the story of a young mother called Marina Fiorato who did not give up, despite her first book being rejected by every major British publisher. She has now gained a £125,000 advance for her current novel and its follow-up in the States, plus a similar deal in Germany. Her historical tale The Glassblower of Murano, set in Venice, was eventually bought by small independent UK publisher Beautiful Books and has gone on to become a bestseller in 21 languages. Marina has also been commissioned to write a movie screenplay for the book by a US producer. This is plain evidence that rejection should not be taken as a valid criticism of your work - unless, of course, there are actual words of warning within the rejection. (If there are, take some heed, for someone in the publishing world is trying to help you.)
I know all about this from personal experience. One publisher even told me a submission I made was the best she had ever received: at the same time as turning it down as 'not for her'! So hang in there and one day your route to publication will be found. Just make sure what you have written is worth the persistence, though, by getting feedback in the form of a professional critique: maybe on just the first three chapters, to keep the cost down. Professionals can tell a lot from that. Or post it on a peer review website and see what the feedback from there is like. Personally, I think this kind of unbiased feedback is far more valuable than hurried feedback from friends in a writers' group, for they probably won't want to offend, and may have given far too little time, anyway, to truly digest your work. For similar reasons, family feedback is usually not very valuable. Peer review authors wanted to read your work, and professionals are paid to read your work. Both, hopefully, have a better idea than friends of what is publishable.
I used a peer review website for the early version of SANDMAN - although the working title then was 'Brief Respite'. Like everyone else, I got good and bad feedback, but thankfully the good encouraged and some of the bad helped me to improve. Build up confidence you have a good MS to offer, then keep at it. A rejection is merely someone declining to go into business partnership with you. Or think of it as someone who would not lift your book off the shelf in a bookshop - and then realise that most readers would not lift the majority of books of that same bookshelf, simply because it was not their thing; that hardly reflects on all the other authors represented on the shelves, does it?
Yes, rejection hurts. But, as an author, you need to harden up and get realistic, it's all part of the process. You need to learn to reject rejection as personal criticism and hang in there. Success will be all the sweeter.