Colleague stole my work and is publishing it as his own; my PhD supervisor supports him; I got the paper to review. How to proceed?
You shouldn't even think about it, do not review that paper, it's a clear conflict of interest, even more because the author is your direct colleague. And the only solution is to sit all together and explain to them that your contribution to said article is significant and you would like to be a co-author. If they have problems with you being a co-author and you have done substantial work then I would seriously consider if you want to be in this research group.