mental health

I really need advice for learning how to deal with no friends. ever since I graduated all my friends seem to have decided one by one that I'm no one. I'm now 25 married and have a 2 year old. my husband works 4pm- 2:30am and I work 6am -230pm. (it's how we have to do it for our daughter.) my best friend was my sister-in-law. we did everything together I have always been there for her. when her friends wanted to keep the party life after she had a baby I was always there. now her old friends are coming back around and I havent heard from her in a week other than one day she wanted me to watch her baby so she could go get a tan with friends. even the birthday plans for her birthday she didnt tell me anything about them and went out with everyone else. I haven't been text or called by anyone other than my husband in 5 days. I feel the lowest i have ever been. if I didnt have my daughter I dont know where I'd be. please help me with advice. I'm truly lost.