You have to handle the situation in a professional way as you will still be colleagues and you have to work together on different tasks.
The first step would be to clear our minds, and think about how we are going to solve this, what we are going to do to solve it.
The second step would be to carry out the solutions, which could be talking to this colleague, talking to the boss,
Finally, reach an agreement with the colleague who is also affected by this situation and between the two of us find the solution that benefits both of us.
