I get like that too, especially if I am really wanting to hear back from someone. It is hard to deal with sometimes. I've also had a lot of rejection in life. One big thing recently is facebook, which I don't go on very often, because I post things and over half the time my family doesn't respond to me, which makes me feel like they all talk to each other but ignore me... So I understand it is hard to deal with.

Everyone has to work around a schedule and schedules aren't always apparent. With PMs and things like that sometimes people don't notice, haven't been online, or are busy. Maybe even just trying to think of a response. But, one thing about PC I've noticed is sometimes the PMs don't go through. This has happened to me several times both with responses I've sent and people responding to me, so it could also be technical issues.

In game, a tell or a whisper that goes unanswered may have been missed completely. Maybe they have their combat screen up, or are in a chatter heavy zone, so it even rushes off their screen before they get the chance to see it. In games that have a "sound notification" of tells, a lot of people have their sound off to watch shows or listen to their own music. Also, people go AFK suddenly and a lot, sometimes for a long time.

I think the best way to learn to cope is practice. Maybe write little notes and stick them to your computer. Little reminders or mantras to chant to try to get passed it. Learning to deal with the past rejections and not project them into the present time. Things like, "Maybe they are AFK." Or... "Maybe they didn't see the PM yet." Stuff like that. Also positive self-reinforcers. On my computer I have this one: "You are the main source of your own happiness."

Other tipes: Take a moment, count to ten, get up from the computer and take a short walk (sometimes physical movement and fresh air help.) Take a shower. Just something to get your focus back. I know it's not easy. Getting triggered into an episode isn't any fun, I know, and hard to put the breaks on and reverse after. But, believing you can take steps to slow it, stop it, and turn it around is helpful too.

It's a learning process.