hi,
Im not in the same situation, but why did the father leave you? I know you stated the relationship isnt the same, and that could be because its not as there is now another person. It will take time to get used to having a life with a baby and will take a few weeks for your emotions to get back to the way they where.
If you feel your not happy been with the father, and the father does not want to see the child because of this, then i would not argue with the father nor be in a relationship to please him. You have to think about yourself and what you want. Obviously it would be great for the child to know his father, but if he does not want to know the child thats his choice. However, in years to come if he comes looking to see the child you will have to let him see it or he may take it to court. If you dont let him see the child, it will look bad for you.
Hope this helps.