Physical & Emotional Abuse Support Group
Abuse is a general term for the treatment of someone that causes some kind of harm (to the abused person, to the abusers themselves, or to someone else) that is unlawful or wrongful. No one deserves abuse, period. Abuse can be emotional, physical, or sexual.

I don't begrudge other people their happiness (and I bet you really don't either), but sometimes I think to myself "that's a person who clearly doesn't know hardship" or some thought like that. But the fact is I really don't know what secrets lie within the hearts of others. Everyone goes through things that are hard for them, and pain feels the same to all of us no matter where it comes from. There may be moments when people observe me and think about how much I have got my crap together, and they don't know the hard work I've put in or the times I still struggle greatly. I'm sure the same is true of you, although you may not know it.
I think when we see other people who appear to have what we want they simply become a mirror for what WE are lacking, not really an accurate picture of who that person is or what their story is. I think it says more about us, and our sadness and the convenient cover up for sadness, anger-that we deserve good things too and we currently don't have what we need.
What happened to you is unfair. What happened to me is unfair. But if I spend too much time in that truth it offers me nothing and takes a lot.
I say acknowledge that feeling of unfairness, accept it, accept that there is nothing wrong with feeling this way and it's normal, and then immediately after replace it with a thought about something you are grateful for, and switch the focus.