It's not something that you will ever "get over" that's for sure. Years ago when I lost my Dad to prostate cancer I had people tell me time will help get over it. That's really not the case though. I guess the best way to describe it is you will learn to live with it, and while you will never get over it you will find ways to move forward and smile again. It takes a different amount of time for each person so don't feel you have to be on any sort of schedule like "I should not feel like this still" or anything like that because losing someone extremely close is the hardest thing in life.
That's what one of the big things that I went though this year was. I lost my Sister back in May of this year at only 51 yrs old. This time last year I had no idea I would be without her a year later. We were the only siblings and as close as a brother & sister could be. Not a day went by we didn't speak with each other, did everything and went everywhere together. It's been close to 6 months since I lost her but there are still times when the thoughts of seeing her for the last time unresponsive in the ICU or thoughts of sitting next to her in the hospital holding her hand and having her tell me how scared she was just come flooding back into my mind out of nowhere and I start to cry. It's just normal and something that I can't help. I'm sure it's the same for you as well when thoughts come rushing in. Don't try to stop those thoughts, let them happen and just accept it and then gather yourself once they have stopped.
It's hard to tell someone this sort of stuff by just typing out things like this, just loses the empathy and understanding when you type it out. But just know that I and others know exactly what you are going through, it sucks beyond belief, but one tiny bit at a time it will become a tad easier to accept and live again. It will be a different life that's for sure, but that's the only option we have when we lose a very close loved one.
While I know what you mean when you say it bothered you that friends would tell you about their friends/family that passed away to cancer, keep in mind they aren't comparing to your loss, they are simply trying to be comforting by letting you know you are not alone in this. It's their way of offering help more than anything.
You ever need to talk to someone or just feel like you need to get your mind off it just hit me up.