I would be livid. I have the same problem with my MiL. OH once applied for a job that needed us to be married. At the time we weren't, as I was still once bitten, twice shy. The job was very near to my inlaws. I told them repeatedly that they had to say that we were married, if they ever met the employers.
We did marry very quietly very soon after, because I hated the lies so gave in - first thing my MiL did was tell the wife that we had just got married when she met her at a dinner! I was so angry, and she couldn't understand why.
No, you have every right to be angry.