Special needs woman keeps coming to my job to talk to me

I need advice. A special needs woman frequents the shopping center I work at and has decided that I am her friend now. I am always cordial with her, hence why she thinks I’m her friend now, but I work front desk and she will come in and talk extremely loudly disrupting the business and will go on for 30 mins easily. She will call the business when I’m not working and ask for me as well. If she catches me outside the building on my way to the car to head home she will follow me and will not stop talking. I am a very nice person and I’ve indulged her but I don’t know how to set a firm boundary with her.

The last couple weeks she’s been talking to me about how her mom is dying of cancer which makes it even harder for me to set a boundary with her because I feel bad. The last two days though she was started randomly commenting on how I am overweight and she used to look like me… like ok???? I’m starting to get very irritated with this. If I’m off the clock she will talk for up to an hour with me constantly saying I’m running late and need to go but she will not stop talking. I don’t know how to create a boundary with her but I need to because this has become too much for me. When I get off work I don’t want to spend another hour listening to her talk in circles. I have a lot of empathy for others but my patience is wearing off now that she keeps commenting on my psychical appearance.

Does anyone have any advice on how to handle this? I already decided that the next time she comes into work (which will probably be tomorrow as she comes every single day now) I’ll tell her that I got in trouble and I really can’t be chatting with random people while I’m working. Outside of work I’m not sure how to handle her though…when I say I’m running late and need to go she will say something about her mom dying that tugs on my heartstrings and makes me hesitant to just flat out start walking away, but she genuinely does not stop talking. All advice is appreciated.