Imagine a friend in a company who was considered a very reliable guy and after a while others notice that there is a big problem with the guy and he was a sly. All of the friends want him to get out of their company and the guy finds no other way other than leaving the group. Imagine once, all the guys have gathered together and are talking about the past events. There are some newcomers and this is why there is a more tendency to talk about the past sweet happenings. Abruptly, one of the group old members begins to talk about that guy who was kicked out of the group. The old member wants to say that: "in spite of that the guy was in the group for a long time, all of us thought that he was a very loyal and reliable person up to the last minute, but when the story... happened, we got that he is a bad individual because he acted like an enemy not friend."
My question: does the self-made sentence below make sense to you to convey this message?
- He turned out as an enemy.
Meaning that: "he was an enemy, but we didn't know it"
Added: I need to know it my mentioned sentence sounds natural in English and if yes, does it carry the message in my question or not?