I'm adopting my cousin's baby...how should we both be feeling right now? Is this normal?

My cousin is 19 and got pregnant last year. She never told a soul nor sought any medical treatment until she was in her eighth month of pregnancy. This is where my husband and I come in. We can't have children and I'm twenty-seven. My cousin offered us her baby because she has no job, no education, no home, support system or even transporation. We agreed and got everything in writing including a power of attorney so that we can make decisions for this baby until the adoption is final. Here is the problem; the hospital let her bond for 4 days. She had an emergency c-section and the baby was in the neo-natal unit because he got sick. They wouldn't let any family in just her and her parents. By the time we got him four days later, my cousin and her parents were undecided on what they wanted. My husband and I agreed to walk away with no hard feelings but once they realized they were going to be emotionally and financially responsible for this child, they threw him at us. Now my cousin is calling crying, confused and she's depressed. Her parents have an attitude with us but we are the ones who got prepared for this baby with a month's notice while they sat around doing nothing. I feel guilty but at the same time I'm resentful. I love this baby but this situation is turning into a nightmare. They want rights to call themselves mom, grandma and grandpa but have done nothing for this child. I feel like I'm going to be financially supporting him but with them always in the way I will never acutally be his "mom". I feel discouraged, lost and broken-hearted. What do I do? Where do we go from here?