I am on my 2nd year of PhD. Some months ago, a woman from another department had similar PhD ideas to me and my advisor's other student. Our supervisor was furious when he realised this and he accused of us sharing our work without authorization. It turns out that my colleague had informed her about our ideas because they were close friends and she copied them. When our supervisor learned this, he was still angry but was not able to do anything because he "didn't have any proof."
At the end of last semester, my supervisor talked with the woman who copied our ideas and invited her to co-teach our lectures next semester. I don't know exactly what her role will be or why her involvement is necessary. I thought this was unfair and I told him so. He was angry at me, but I don't regret it. Since that time our relationship is very cold and way more distanced. In fact, I am worried he wants to replace me with this student who stole my ideas.
So, I am wondering: is my anger justified? Should I have concerns about the woman who copied (or at least, inspired herself too much from) our ideas? And at my supervisor for offering her a place at our lectures? I know my supervisor is a head of a department and it is him who makes decisions but I felt that this situation was unfair. Additionally he would accuse me of being unfriendly and not cooperative.