newly single

I am 17 weeks pregnant, my husband and I separated over a month ago. we still live together due to living with my parents for previous reasons.. he says he wants to stay here to support me and our baby, so I have been letting him. hes been involved with another woman who has 3 kids of her own, he talks to her every day. he hangs out with her from 11pm- 6am or later. it hurts me so I'm telling him I need him to leave. my question is.. if you have been in a long term relationship, how did you learn to be single again? how did you learn to live life alone? and if you did while pregnant/with a baby involved? I'm tired of hurting and I need to be strong for my baby.