Job legal case on employee

Few days back a uk client came in with a project to our company and it was assigned to me i was working on it client initially didn’t share much details about the product shared is old code to upgrade which was simple system and after 2 week he shared the spec doc and all we were having good work many times h came up with good work in the end of the 10 week.he mentioned there was deadline at first week which was missed and cost us 2 million dollar and there was no legal contract signed for this deadline .now client is angry and saying he will file case on me not company for this damage who is responsible please adivce