Supervisor gave my PhD project to another student

You know for the most part supervisors are smart enough to handle their students and their research groups. However, once in a while, there will be a problem either with the student and/or supervisor. So two things here:

Know You Rights and Hierarchies: Simply know what your rights are in your institute. Moreover, know the hierarchies. For example, who is the boss of your supervisor, or even, who is the boss of the boss of your supervisor? You know where I'm going with this? This bring me to the second point.

Be Vocal and Express Yourself at the Meetings: If you sit at your desk and pretend everything is fine, and your supervisor manipulates the situation (assuming you are telling the truth here), then YOU are the one responsible, because you didn't speak your mind. Have a meeting with the head of the group (your supervisor's boss) and speak about it. Tell him/her your story and situation and he/she should sort this out. If you couldn't sort it out, have a meeting with someone higher. They are there to help you.

If this was really the way you were treated - by which I mean that you have to be sure not to misinterpret statements or promises of your supervisor - then you should run.

A PhD requires trust between the supervisor and the student. After such a breach of trust, you need to find a new supervisor.