How did the mexican government feel about the annexation of texas by the united states?

Though Texas wanted to be annexed and had voted within their independent nation to become a part of the US, Mexico had still not settled Texan independence and therefore was upset by the US's move to annex Texas. There were many boundaries unsettled after the Texan Revolution and this will lead to issues between Mexico and the US in determining the border. These border disputes coupled with contempt for US actions will lead to the Mexican-American War in 1846. This war will end with Mexico losing all of what is now the SW of the US in 1848 under the Treaty of Guadalupe Hidalgo.