i'm terrified that by marrying him i will always be second to his computer.

You're currently second, so why do you think marriage will change this? MARRIAGE DOES NOT MIRACULOUSLY CURE BAD BEHAVIOR. MARRIAGE INTENSIFIES IT.

He complained that i've been nagging him about this for two years and i said that it is an issue that I have been complaining about this for two years and he still can't see how detrimental it is to our relationship and then he said that i was twisting his words and trying to cause an argument and to leave him alone. he then put his head phones on and started playing his game.

When someone tells you who he is, BELIEVE HIM.

He has told you the truth here. He is never going to listen to you BECAUSE HE DOESN'T HAVE TO. He trusts that you've subscribed to the sunk cost fallacy and won't ever leave him. He's faced no consequences that pain him in any way, so...why should he change?

That's the question: Why should he change?

I'll guess that housework, cooking and all the emotional labor fall onto you, yes? And that you fuck him whenever he's in the mood? So...why should he change anything so long as all his needs are being met?

What do you get out of this apart from Not Being Alone? (Please don't tell us, "Sometimes he's so sweet!" and/or "But he sometimes cuddles with me!" Pleasepleaseplease don't tell us you're settling for so pathetically little).