I am a bit surprised at the huge emotional attachment you have with him to be honest.. It was a 5 week so called relationship... There wasn't really any part of the relationship that even came close to a healthy connection.

His addiction is his life right now there was / is no room for a relationship with a person like this.

***Did his mum convince him that I was trouble? Did he suddenly realize that by himself? Is he after someone else? Did he cheat on me and is his conscience killing him? I don't know anything.
I just want a straight answer and I don't know why he is too cruel to give it to me. I helped him to get home by lending him money. He was so grateful but not enough to be honest with me 7 days later it seems.***

All those questions ? you will probably never get a answer for..You loaned someone money to go. home... and get help and now he wont speak with you... Take that as a huge sign.. He isn't worried about your feeling or your financial help or being a decent human being in general.

Its ok to be hurt ., it's okay to be angry. it's really not okay to beat yourself up over something and keep wanting answers from him... that probably will never happen. Sometimes you just have to let it go and move on.. Not all relationships end with all the loose ends tied up in a tiny bow.

Sorry your hurting .. but take the power back and focus on the future.