I bet you'll be forever haunted with this for the rest of your life if you're deciding to terminate your infant's life or to give it up for adoption. one day, when you're an old man, you'll probably be constantly reminded of him/her. For now, you yet to feel the guilt. Who knows maybe you'll feel guilty afterwards or when by the time you're old. Maybe, one day, he/she will be looking for his/her biological parents.

For your infant's sake, I would consider the adoption as the best option though. It's better to let a pair of parents who can't conceive who would shower your child with love and care, rather than having a father who wouldn't want him/her in the first place, just mainly because his/her physically unattractive mother.