Single and pregnant

So this is only my second post but I thought I would give it a try... I am newly single and also pregnant! The babies father decided he didnt want to be with me anymore the day before we were moving in together. I am now 28 years old and living with my mom so that I can get help with the baby when it comes. I have never felt so lost and alone in my entire life. Left wondering how someone could do that to another person? How do you tell them you love them and you'll never leave them and the baby and then just walk away? He still wants updates on baby and wants to be in it's life... but what are thoughts on using my own last name and not his?