From: Rabbi Moshe Sofer
To: Rabbi Avraham Shmuel
A single witness testified to a kiddushin in which the word 'li' was omitted from the formula, the groom denied the entire event, and the woman stated she had no intention of kiddushin. The Chasam Sofer rules on multiple independent grounds — including the invalidity of one-witness kiddushin when the groom denies it, the defective formula constituting yadayim she'einan mochichos, and the mashta defense — that Fayerl bas Moshe is entirely free to marry without a get.
Source: Shu"t Chasam Sofer EH I §99