Can't see the postive - tough week

[Littlemissnutcracker]

Namechanged. I work in a tough environment with poor leadership. But pays well and there is high unemployment in the area I live in.
But as it happens maybe 10 good things happened to me this week and one bad. I end up in tears over the one bad thing. This is a bit hormonal I know but how can I get out of this mindset.

Where I work there is a lot of favouritism and unfairness. People get promoted due to friendships with the manager. I need to get beyond this and be happy. Any advice?

Also I can deal with criticism well and take things very personally. I think this stemmed from my upbringing when it I ever achieved anything my mother eye rolled or dismissed it. I have been very successful in my life since marriage wise and work wise but I carry this heavy burden and sense of being seen as the village idiot at work despite being the highest qualified