WDID Reddit....

this is my first time using this app and i dont know how it works, but i need someone to ask advise about for this, so i am under 18, (I wont say how old i am for my safty), But i just found out my mom is still talking to my Ex step dad who SAed my last year. i found it on a criket phone of "I love you baby" and other thing i wont say.....i am hurt i am getting PTSD flash backs, i am going to talk to my therapist about this.....my mother is at work RN, but she has lied to me for a year now...she made me feel bad about a 8 year relationship....she told me she belveved me....but now im not so sure.....please reddit i need help....what do i do?