I wonder what Hetalia group that is, cuz I know my friends and they don't sound like that (Cuz trust me, there are a LOT of Hetalians on here, I being one of them. Not all Hetalians are bad btw.)
Yes, people are rude. It's upsetting. I mean, I'm not on all the time, but I do manage to find the nice people. It's like people going anonomously onto those websites (Like Tumblr) who go and say mean shiznits like "you're ugly" "No one likes you" "Go die" Etc. It's not okay and anyone going thru that doesn't disserve that. Personally, I don't know WHY people can be like that? It's just stupid and really messed up.
I'm sorry this happened to you. It's not right. This game was ment for fun and friend making. Not this. The best thing like PieStar said is ignore and block. And if it does become to bad, then contact a mod.
Also, the best thing is honesty. If you don't want to rp or hang out with someone, one should say so. And that person should understand. I have it bad because I get constantly talked to by these 2 people who really like my maps Glen Isle and Spancil Hill. I don't have the heart to tell them to go away or anything. But if I'm role-playing with a friend or exploring a map, or even recording for a video, I tell them. I tell them my replies will be late and such. Hopefully they understand (I mean they say okay and everything but still) That's some things people should really get. Honesty and understanding that honesty.
That's all I have to say. I hope it wasn't too bad for you.