Both are correct. "I cried." and " I was crying." But 涙する is a literary expression. It may sound unnatural depending on the context. In a regular conversation, simply saying 泣いていました would sound more natural. To describe a situation, you could use it as in "彼女の歌に感動して、皆が涙していました。" or ”あの時、私は彼の言葉に涙した。(in a piece of writing)”