Betrayal

What is the meaning of "betray"?
Based on the oxford dictionary, the verb "betray" means "to hurt sb who trusts you, esp by not being loyal or faithful to them". If this impies, then I am betrayed, we are betrayed!

I am angry when this happened! It couldnt happen. It shouldnt happen. From the beginning, I still put 100% trust in them. I trusted that they would not betray us. I trusted them for whoever they are. To my dismay, I found out that one of them betrayed us, letting us into hot water... I am angry! We didnt force them to join us. They beg us to let them in and this is what we get in the end! And we were stabbed from the back now!

I am wondering what is his or her feeling now... Happy? Clapping hands? Celebrations going on? I dont know And I dont want to know... I dont care. I just want to know who did this to us? I just know that we are hurt by them, badly and mercilessly.

I am not sure whether or not I could one day forgive them for their act. For now, it is still hurting...

For once, I anticipated the day they arrived.
I hope to have a good relationship with them all.
I want to treat them nicely. Maybe go to K together, eat together, shopping together, doing crazy things together...
I want to help them out for whatever problems they face...

But now, I am utterly disappointed and sad...