Opening up about Harm OCD to a partner?

TLDR: I have harm ocd and intrusive thoughts that center around a fear of hurting my loved ones. I haven’t shared this with my partner of two years and my NOCD therapist thinks it might be worth bringing her into a session and sharing about it with her so that my girlfriend can help participate in exposures. I feel really apprehensive and don’t know what to do. I’ve been with my current partner for over 2 years. I love her so much, we moved in together about 7 months ago, we have a cat together. I’ve had OCD my whole life, and it’s almost always been centered on themes around harm. I have a deep fear of losing control and harming someone, going crazy/ going into psychosis and causing harm, constantly scanning myself to see if I have intent, etc. Obsessions about harming myself as well. It was hell in my young adult life throughout high school, even had a freak out while driving on the road once that I was driving (when I was 17). When I went to college, I started on lexapro and my symptoms became very manageable. I still went to therapy for other reasons related to trauma, but I almost never talked about OCD in my sessions. It was just like white noise in the background, sometimes popping up but never anything severe. I met my partner my senior year of college. In the time we have been together, my OCD had been relatively quiet. That is, until about two months ago when a combination of triggering news events (the Lindsey Clancy trial), stopping therapy and not taking my meds sent me into the worst OCD spiral I’ve had in years. I was having terrible intrusive thoughts about what if I caused harm to my cat or my girlfriend. It felt awful. I started having severe panic attacks, I felt unsafe to be in the house, I was avoiding daily activities, feeling suicidal. I have gotten myself a bit back together, back on better meds and therapy routine, and stuff still feels harder and scarier than it used to, but I’m getting back to my life slowly. But now that I’ve started working on exposures with my therapist, my therapist wants my girlfriend to help me in doing exposures because a lot of my fears revolve around hurting either her or my cat. My therapist said that my girlfriend could join a session so that my therapist could help provide psycho education. But I feel so scared to share about what I’ve been experiencing. Obviously since I live with my partner, she knows that I have been going through a mental health crisis, but I haven’t shared much about the content of my thoughts, just that I have extreme anxiety and dark thoughts that cause me distress. I feel so scared that if I share this with my partner, that she will be terrified of me, that our relationship might never be the same. At the same time, I feel so guilty feeling like I’m keeping this massive secret from her - we are so in love and share everything. It’s made me feel disconnected from her. But I’ve never shared the content of my thoughts with ANYONE besides my parents and my therapists. I feel like sharing about my thoughts could ruin everything - a two year relationship, our shared apartment, our shared cat, our shared friends. But it could also be bad to not share it, and for her to find out later - I guess it’s better to give her an out now if this information scares her. What would you do if you were me?