Dark skin on crotch like between upper inner thighs of bikini line?

Also I am very self conscious of having sex too because of this...will the guy care? :/

Well it depends on the guy on whether he'll care or not but as far as the dark spot it's probably there because your thighs rub together as you walk . Don't feel bad because it's not only you most girl with big thighs have this problem. And I don't really think there is a way to get rid of it, I mean you can try but your thighs would still rub together so it's gonna be dark regardless of what you try and do to get rid of it.