Awkward situation

Hi ladies, I have a really good friend who I see very often, she has a little boy who was born just two days before my little girl. They are currently 2.5 and have known each other since 6 months. They used to get along great however the last 3 times we have saw them her little boy has pushed, hit, pulled my little girls hair, grabbed her arm, thrown toys at her etc. The first time it happened I thought maybe he was just having an off day, the second time I told myself we’d take a break from seeing them as my little girl was left upset. I understand hitting etc can be normal toddler behaviour but it’s so sad for my little girl who is the gentlest softest soul and is left upset when she understand what’s happened (she then copied the hitting for about 2 weeks after seeing them). We saw them yesterday and it was the worst, it was constant to the point we left their house and went for a walk instead to separate them. I have no idea how to move forward, I obviously put my daughter first and won’t put her in a situation where she is in danger however I just don’t know how to handle it with my friend as she obviously apologies but then asks to hang out again the next week..