(29F) Dealing with a terrible fear/thought loop about my dad

My dad is a kind and honest man. He has many faults, he does stupid things, but he has always gone out of his way to provide for us. He is a loving person and a supportive father. He also has brain damage from a traumatic brain injury, which is important context for what I’m going through right now.

Unfortunately I have always had a deep seated distrust and fear of men (from early childhood harassment from family members/grown men) and I have at times projected this distrust even on my dad. A couple years about I was in the bathroom mirror wearing a swimsuit getting ready and my dad stood behind me, asking if I was working out because I was looking toned and athletic. He didn’t SAY it in a weird way—he takes pride when me and my siblings when we look healthy and well put together. It was the fact that he was looking at me for so long that felt really uncomfortable. I felt he was beholding my body, and the mere act of that made me question what was going on. Again, he tends to zone out or look weird because of his brain injury, so there is that factor.

A year after that, the same thing happened. My dad complimented my outfit, and was standing behind me in the mirror. I felt like he was looking at my body, but it’s hard to say it felt like leering. I am much shorter than him (5 ft) so at the time my fear was “he’s looking at my butt” (I share the same pear body type as my mom). I can see now how my height plays into what I think someone is looking at, especially if they’re standing behind and I’m seeing them in the mirror. But I instinctively reacted with extreme discomfort.

Eventually I privately confessed how this all made me feel. He reacted with sincere despair, revulsion, and was mortified that I even thought that’s what he was doing. He was depressed about it for a long time and told me it forced him to be more mindful of how he interacts with us so he’s not taken the wrong way. I felt depressed and guilty that I made him feel that way. His reaction was reassuring that he didn’t mean it the way I feared. But my OCD brain keeps trying to replay the moment, to be 100% sure. My gut says my dad is not pervy and wouldn’t do that. Yet I’m unable to figure out why my feeling at the time was so strong and so skewed. I’m unable to fully picture how his gaze looked or all of the details of these moments. My mind keeps looping trying to peice it together, and I can’t, and it’s driving me insane.