Spiralling into depression

I'm seven months pregnant and I also have a 16 months old. With that being said I'm currently staying at my children's father mom house while we finish our place. Things haven't been easy his mom repeatedly insults me saying her son could have done better and how I make people around me miserable and if it wasn't fore having children for him o wouldn't be here and the list goes on. Well my boyfriend isn't much help because for one he is quite and his mom basically controlls him and two he is actively cheating on me. I just feel tired in this situation o cry repeatedly I think about self harm and the only reason I don't go through with it is because of my daughter. I just don't know what step to take with all of this.