Things That Make You Wonder .... "WHY"

Over the last few days, I have been finding various things out, and I don't like what I see..
I run graphics through a friend page on Facebook, and over the last few months I have come to meet some nice people, some not so nice.
Worst thing is, the not so nice things come from someone whom you classed as a 'friend'
Everyone has their opinions, I am not saying they don't, but surely if you had a problem with someone you would therefore explain it to someone to hope to solve the differences or just brush it off and ignore it because you know full well that saying something would cause drama.. Or so you think!
I've been hurt and distraught over people taking advantage of me, and reporting me for silly little things left right and centre, but never did I expect to see it come from someone whom you class as a friend..
1st problem - made a graphic to print, laminate & post - which I did, but then claimed never got it and then set a month long problem with PayPal.. Got their refund & their graphic *sigh*
2nd problem - made a timeline cover & display picture to help out a 'friend' for free - stole my design stuck them onto t-shirts and sold them *sigh*
3rd problem - a 'friend' criticise my work, wrote how they wanted to hurt me, and blocked me from seeing everything on their page - god knows why :\ and now I think I've fallen out with my friend over it..
This is the 3rd thing to go wrong since doing my graphics, all in the space of months! Something is starting to tell me that maybe I am wasting my time and efforts in doing what I am doing, and I should just give up..
Another part of me is telling myself to not give up and let these people win, because there are people out there whom have come forward and told me how my work has helped them grieve and so much more..
I don't want to let people down, but I don't want people criticising me and being generally rude for no reason at all.. I've never criticised them or their work, and I have been doing what I do for the last 7 years, not to mention the 2 year gap! But I still designed websites for friends..
Really wish I knew what gave people the idea to say things like this, especially to fellow designers and friends!!

I get a lot of my inspiration from other graphics.. I look at them and think
" ohh wow I like that, I wonder if I can do it too "
And so I try, sometimes I fail, sometimes I don't..

Its not my fault a lot of the scrap kits are free to download, some are to purchase.. Not to mention having over 1000 of tubes!
All my work I do in Paintshop Pro X2 and I love it and love using it.. I am always learning new things.