I used to be similar to you. As a child, I raged incredibly hard whenever I lost to a CPU, "I am a human, I'm better than them!" I would shout as I slammed my controller into the ground. Funnily, I was never that way against humans, I just broke into a cold sweat and smiled at them and laughed with them as I got wrecked.
One day, I have no idea when, I began to view my rage with an even stronger disgust, it was a poison that only served to further enhance my despicable state, but I worked and worked to solve it, and then became just as you are, I hated losing in any way to anybody (most especially random people on the internet) or anything (dumb CPUs!), and I stayed like that for many years. I still do have a hint of that nowadays, but I did change.
Nowadays, I am at peace. But how, I wonder? Two things I know for certain, I was prideful, and I changed that attitude through sheer force of will, that's it. If I, bonehead that I was, can change myself over any period of time with a sheer force of will, then you can do it too, I know this for a fact. I know that all humans can do this, for we share the same essential nature as rational agents of will.
First, you've already acknowledge your attitude as a problem, you acknowledge that you are prideful. This (pride) is the most major defect you have, it is far greater than any ability to learn any technical skill in a game. You're already on your way. Second, to begin your journey of change, you have to believe that you can change anyways. Third, you must have the desire the good and hate the bad.
If you have trouble with any of the above, there's a simple way to get around wanting to change. Want to want to change, and if that's not possible, want to want to want to change. With the degrees of detachment it becomes easier and easier to desire and strive for something, and you will eventually work your way up to desiring the actual thing, and then attaining it.
Perhaps by now you've stopped reading, justifying yourself saying that you don't need to change. My point is that you can change, and this pride is a serious, massive defect in your character that needs to change. Pride is the keystone of all other evil in anyones lives, all evil can trace its way back to pride in some way, shape, or form, and it must, above all, be attacked (not necessarily destroyed the first time around, that's just ridiculously hard) before one can work on their other various defects.
You will continue in this miserable, deplorable state until you change yourself, and believe me, you can change yourself as I have. Once you do, you will find a greater peace. Fact.
Now get over yourself and start calling yourself filth instead of others! That seems like a good starting point