My body failed my friend...

I agreed to be a surrogate for my friend and his wife. I even signed papers donating my egg to them. The wife couldn't use her eggs, so they had donor eggs and made embryos. I was prepared for a transfer, but then things got bad between him and his wife. He found messages on her phone of her cheating on him, so they put everything on hold. He wanted to work on their marriage, so everything was put on hold. They went to therapy and found out she didn't actually want a baby. He didn't understand why she had lied for so long, but he decided to give up his dream of being a father and hope that maybe one day she will change her mind. He came over to my house upset one night. We talked and he found out his wife was talking to a 17 year old boy. She's 38. The conversation were very sexual and he was done. I was there for him through all of that. He got very depressed, so I would call him and make sure he's okay. They went to court and stuff for assets. She signed papers saying the embryos were his and she didn't want any rights to them. After he had done some work on his mental health and was in a better place, he came to me and asked if I was still okay being his surrogate and he was gonna go through and have a baby anyway. Of course I said yes so we went through the process again. He was so happy when we found out I was pregnant. Baby was growing doing well at the appointments. Then idk what happened at 11 weeks... Before baby had a strong heart beat and everything seemed fine. When I was 11 weeks, I had intense cramping and started bleeding really bad. I was gonna go to hospital but went to sit on the toilet and everything came out.... I just new it was a miscarriage. I called my doctor crying and she told me to scoop everything up and take it in so they can try to see the cause... I called my friend and he sounded like he was in disbelief. It hurt so bad to make that phone call... I did in fact miscarriage. I cried... He cried.... Worst part is there wasn't a specific cause... My body just failed... My friend kinda wanted to be left alone for a bit. I failed him... My body failed him. I feel like the worst friend ever. I've been wanting to reach out to talk but idk if it's too soon and maybe I should give him more time. I don't know why my body did this to me... why to him... what is wrong with me?