Such relationships are not allowed in Islam. Islam calls for purity and modesty, and marriage as the only way for two people to be together.
Ruling on taking boyfriends or girlfriends
You should work towards ending this relationship at a personal level. And talk to the peson himself and tell him you don't want this but rather want something more pure and better (marriage). Tell him what he is doing is haraam (forbidden) and that he should talk to his parents about marriage.
Also, you should talk to his brother as well. Tell him that you just converted and are still learning about Islam. That you just found out about this not being allowed in Islam and that you would rather get married then continue this. And that you do not wish him to stay over at all and would like him (bf) to talk to the parents.
Lastly, I heard the asian guys there aren't too serious about islam or non-asians. they will be your bf and have fun but marry only their own kind. Not all people are the same but a precaution should be taken. Also, go to that forum link i gave u in PM last time. You can find lot of good sisters there that are in your area. They can inshallah help you transit and guide you with dos and don'ts so no one take an advantage of you.