Just wondering what your relationship with your gran was like, ie was it very significant to you and impactful when she passed? I can tell you that I never had the same anxiety about sex before I gave birth. I know it's a completely different matter but my psych team told me that the significance of that event changed things. Remember people react differently to their trauma. Some sexual abuse survivors become overly engaged in sexual activities, others completely avoidant. I believe I swung from one extreme to the other before and after giving birth.
You did say that any help would be great, and so I'm curious as to what kind of help your T is offering? Because it would be hard for anyone here to advise on what's most appropriate to you specifically. Personally, I've had to try a lot of different skills before I felt like anything could ever help decrease the anxiety. I do find dbt helpful, specifically paced breathing, and paired muscle relaxation. I also find mindfulness beneficial. But for me it's a fine line between panic and dissociation. And so I encourage that you work on developing coping strategies with your T as they take time to master and implement even in the least stressful scenarios.