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How do I tell my husband I don’t mind if he has sex with other people?(r/DeadBedrooms)
EMDR therapy is remarkably effective in helping people overcome sexual abuse trauma like the kind you describe (specific issues with penetration)
Some therapists offer sliding scale to make treatment affordable for people who need it. You could look at it as a good investment in yourself and your relationship.
Healing Sex: A Mind-Body Approach to Healing Sexual Trauma by Staci Haines
are both fantastic resources recommended by many therapists