Have sensitive and slightly red skin on my cheeks after using 0.2% betamethasone valerate cream on face to get rid of an excezma like break out ?

Stop using it.: Betamethasone is a strong steroid cream that should not be used on the face. Short-term it will cause sensitivity such as what you experienced; long-term it can cause "rebounds", where the rash comes back with a vengeance when you stop using it, or even rosacea. Try an otc Hydrocortisone cream to get rid of the rash, and if that doesn't work, see a dermatologist.