I can't get over a sexual assault that happened almost forty years ago?

Get counselling. It is not uncommon to still have "issues" post sexual assault, even 40 years later. It can harm future "normal relationships" psychologically. Please seek out a therapist or inexpensive "counseling service".

Related Questions

Can you tell me how I could get over and move past my sexual assault?

Talk. With a psychologist or other therapist with a specialty in treating sexual trauma. Also, connect with other survivors of a similar trauma (e.g. rape, incest, etc) so that you see you are not alone. Take care of this, Read more...