Missing Parent & Adoption

My engagement ended very badly before I learned I was pregnant, but the father wanted nothing to do with me or the child. He even wrote to me to tell me that we are "dead" to him. I didn't want any problems regarding custody, child support, visitation, etc., so I didn't put his name on the birth certificate. My daughter is now 3 1/2 yrs old and has never seen her father. He lives only 10 minutes away, but refuses to see her even to this day. I tried one last time for my daughter's sake this past x-mas, but he still rejected the idea of ever knowing her. I am now engaged again and my fiance would like to adopt my daughter after the wedding, but in NY the biological father must consent to it unless deemed 'unfit.' What constitutes 'unfit'? Her natural father has never seen her, never paid child support, rejects every attempt at communication...does this mean my fiance and I can avoid needing his consent? And if we do need his consent, do we also have to subject my child to DNA testing, to prove paternity since his name is not on the birth certificate, even if he admits he is the father? Anyone with answers or advice, please respond. This situation is putting alot of stress on myself and my fiance during a time that should be joyous. Thank you in advance. Sincerely, Claire.