Sorry, you will need to use this construct with "orm", "ort" .... From Irish this construct with a noun is translated into an English adjective.
If you wanted to use "tá" and "mé", then these would come after each other, and still that would not be a grammatical correct structure (i.e. NOT: "Tá mé brón") because connecting a pronoun (mé) with a noun (sadness / sorrow, or e.g. 'pupil'), requires the copula (is): "Is dalta mé".
Please do take a quick look at teanglann for the use of brón:
There are later similar constructs with other nouns:
- Tá áthas orm = I am happy
- Tá ocras ort = You are hungry