I Need Help Please

I was sexually abused for about 5 years by my biological father. I was also neglected as I rarely has food and never balanced meals. I have been diagnosed with PTSD, BPD, OCPD. I m really struggling with my step son who lives with us and has for he past 6 years, he is 19 now. About a year and a half ago he started sneaking up being me and just standing there until I startled then he would just walk away. I d inquire what his motive was and with a crooked grin he d smirk, give a grunt... I Need Help Please
https://www.myptsd.com/c/threads/i-need-help-please-3.52256/