Q: I am unable to even have a conversation with people who "do it" differently from straights. For my part, I wish they would all just disappear. I feel really ill when I think about it; yet I can't seem to stop thinking about it!
A. When I have a conversation with other individuals, my brain is focused on the conversation we are having and the topic under discussion. My brain definitely does not think about how they might “do it.” It never does.
Your comments (I don't find a questioin) implies a rather stereotypical assumption about how people "do it." Undoubtedly, there are as many ways to engage in sexual behaviors as there are people doing so.
Choices about sexual behaviors are not necessarily consistent with a person's core gender identity. My years in public health certainly taught me that. For example, there are cultures in which rectal intercourse between males is perfectly acceptable when a female partner is pregnant. In their view it has nothing to do with an orientation toward being either straight or gay. As one man put it, "It simply has to do with sexual release pure and simple—and beats masturbation." (I was tempted to ask him to define pure and simple sexual release but I didn't. It certainly has gotten him a sexually transmitted disease.)
There are also cultures in which rectal intercourse is considered to be a perfectly acceptable form of sexual activity for a female prior to her marriage, in order to make certain she is a "vaginal virgin" at her wedding. And there is a sub-set culture in male prisons in which rectal intercourse is practiced, even though those same males exhibit that behavior only while incarcerated. Once out of prison, they reportedly revert to heterosexual behaviors—whatever those may be. And I could go on. If everyone who "did it" differently (and differently from whom?) just disappeared, a sizable population would likely disappear from this planet.
What you choose to think about is one of the few things over which you have control (assuming your brain is functioning within the parameters of a normal brain, so called). If you can't stop "thinking about it," and you feel really ill when you do think about it, you must be spending a lot of time feeling really ill. That would be a choice, of course. Yours. If you truly want to get a handle on this (and you may not), decide what you will think about. Select several healthier replacement thoughts. Use your willpower to help you focus on the replacement thoughts you have selected.