I think my fantasy will take over my real life
What makes you think your fantasy will take over your real life?
Because it comes to mind a lot and I consider making it a reality
If your fantasies are unrealistic or hurtful then you should control them. Being obsessed with fantasies can lead to delusional thoughts.
It just a fantasy, there's nothing wrong with it.
I believe it is wise to just be aware that your fantasy is separate from reality. This way you are going to remain in control.