It is better to have an open enemy than a false friend for a lot of reasons.
The first reason is that if you had an open enemy, you would know that person doesn't like so you will not tell him any secrets or personal things because you know for sure he will tell somebody else. If you had a false friend, you would tell him secrets and he would tell everybody which will not be goof at all.
The second reason is that if you have a false friend, you will get attached to that person and that person doesn't even like you, so you would feel hurt.
The last reason for which it is better to have an open enemy than a false friend is that the false friend will lie to you when you would ask him to make choices for you and choose the bad option just so you could be hurt.