How to cope with my daughter giving up my grandchild? (Long but I need help)?

Right now I'm grieving for my grandchild that I'll never see again. My daughter turned 18 a month ago and I haven't spoken with her since her birthday. She gave birth to a baby boy three months ago that she gave up for adoption. When she told us she was pregnant we were disappointed but that disappointment deepen when she said that she didn't want to raise the baby and was going to give it up for adoption. My husband and I come from families that don't really believe in abortion or adoption so we were deeply disturbed by this. We asked her to reconsider her decision but she said her mind was made up. The boy she was dating at the time wanted nothing to do with the baby and his parents were all for the adoption as well so we got no support from them. Everyone in our family tried to talk some sense into her. We were all willing to help her with the baby physically and financially so she had no reason to want the baby to be adopted. I asked why she wanted this and she said that she wanted to have her own life and go to college not take care of her mistake. I told her that the baby was a gift not a mistake and she got angry. We had a fight and she moved into a friend's house until the baby was born. Me and my husband consulted with three different lawyers to see if we could get custody of our grandson and they all told us that 1) they couldn't do anything until her rights were terminated and 2) by that point it would be too late if she's already found a couple willing to adopt the baby. Apparently one of them got into contact with her because she called me screaming saying that she's already found a couple to adopt the baby and to stay out of it. After 2 months of me begging, she invited them to our house for dinner and I asked how often my daughter would see the baby and they all looked at each other and the woman said they agreed to a close adoption and that they were moving across country after the baby was born. I lost it. I started screaming at her asking why she was doing this and did she have any clue how her child would feel when he found this out. She said that she didn't care about the baby and that I wasn't going to stop the adoption and I told her she didn't deserve the baby and she told me to go to hell. I didn't speak to her until she called me from the hospital after the baby was born. He was so beautiful and I just fell in love with him. I begged both (my daughter and the father) to reconsider and she told me to "get over it. Its done. The ink is dry. Move on." I was so angry that I left. I saw her again about two weeks later when she came home. I thought she must be an emotional wreck and I felt guilty about that but she was happier than ever. I waited to see if she would bring up the baby at all but no. I finally brought "him" up a week before her birthday asking why she didn't care about her baby and she screamed at me saying "that baby was a mistake that's been corrected. He has parents that care about him so get over yourself." I told her I'll never forgive her and she moved out for good. I know I shouldn't have said that but I'm in a lot of pain right now. The couple have moved and my grandson is gone forever. How do I cope?