I need some advice,

Hey everyone I just wanted to ask about an event that happened to me today and get some input on it. A little context this was early in the evening and my manager had to go to the back to deal with some personal stuff and she left me alone up front. I’ve only been working at a pet store for a couple weeks so I’m still new to everything. So I was sitting behind the register when an elderly man come into the store, I couldn’t really understand him so I leaned over the counter to talk to him at first. He was asking if we have dogs he can buy and I told him that we only have a foster cat. He got a little louder and said that he wanted a dog, trying to help this guy I came out from behind the register and pulled out my phone to show him a website for a local shelter that has dogs. He handed me his phone saying to just do it on his cause he didn’t know how to use google, so I took it and tried to show him how he could get to it. At the beginning of our interaction I was leaning the top half of myself to show him the screen while keeping a respectful distance from this complete stranger. While I was showing him the site he had pulled me closer to him and he started to get a hard grip on the back part of my hip and he would rapidly move his hand down then back up. He also moved his grip to my bicep and with the same level of force, digging into my arm and hip. I didn’t really know what to do so trying to be nice I told the guy that I could go get my manager as she’d know more then me but I was to scared to actually move out from his grip. After a couple minutes of me trying to politely get away my manager showed up to the front and I tried to signal to her to help me but as soon as she come he backed off me and I sped walked to the back to collect a chair for him because he was complaining we had no where to sit for the elderly. My manager called the police but the store was so busy at that point I tried to stay as calm as possible while having a slight panic attack and check people out. I am someone who likes to down play what happens to me to prevent feeling the full extent of what happened so when I told my mom she freaked out and told me it was sexual assault and I need to make a report. This man is apparently a serial molester and just got out of corrections for assaulting a kid across from me where I work. Where I struggle with thinking of it as sexual assault is he never grabbed the entirety of my rear and I can’t help but beat myself up for not just telling him to stop and getting away. So can anyone help bring some outside perspective.