Step dad tried to hit on me and my sister!!!😑

Ok so my step dad came in my life when i was 11 years old (im 26 now) and not too long ago he made a fake facebook account as a lesbian woman(cuz he knew i was onto girls) to try and hit on me and convince me to send him nudes!!! I had mentioned to my mom about this person being so persosten on trying to talk to me.and showed her the profile and she said that person was doing the same thing to her we where putting 2 and 2 togetber and found out it was him( hr was trying to get dirt on her to later throw it in her face tjat she would also be unfaithful to him)...then i told my sister what was going on and she told me that same person was messaging her too trying to get at her...my mom was so devastated and felt ashamed of what he was trying to do with me and my sister....she got mad at him but never left him 1 yr after he created another account and he attempted to get nide pic from me and my sister) i feel so disappointed so disgusted because he was the only close thing ive ever had as a father ( i never met my father) it has changed everything i hardly even visit my mom and younger siblings because of it...i dont feel comfortable around him any more!!! He has asked my mom my sister and i forgiveness but he also did the very first time we caught him and i just dont believe him.i though my mom would leave him for disrespecting us all like that but she was just mad at him for like a month or 2 (he would sleep in my brothers room,and she would do her wife duties for him like wash his clothes cook for him etc) after the 2 months i guess they reconcile...i expected my mom to show us we r worth more to her than her man....she said she didnt leave him because of my younger sinlings they are super attached to him (his 4 kids they had together...but mainly my 7 year old twin brothers.) Ever since I keep a pretty huge distance between him and my little family.