Girlfriend's snapchat "best friend" is ex. Should I be worried?

My girlfriend has been going through a tough time. It was the anniversary of her brother passing away. Her ex's mom (who she was really close with) has cancer. Her ex is in bad shape too. Well he lives 5 hrs from her. The relationship ended with him cheating on her a lot.

She's said before she never wanted to get back with him but misses him as a friend. So I checked snapchat and her ex is the one and only "best friend" on there. Meaning she must have been snapchatting him a lot. She admitted to talking with him because of his mom's situation, but now I'm starting to get suspicious.

I don't want to go all jealous boyfriend-y and call her shit out, but it kind of hurts and I don't want to accuse her of anything bad. Should I distance myself?
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She and I are also long distance, but we both love each other.
Girlfriend's snapchat "best friend" is ex. Should I be worried?
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