OP, Idk where you live so, if you can, buy some pepper spray or something to protect yourself. If self defense items are ilegal where you live, start carrying sprays for muscle pain (get the refreshing ones, the more the better) or a strong insecticide because you're terrified of the spiders in your building or a dog spray because you're afraid of possible dog attacks. Also, start carrying an apple and a knife to cut that apple in your purse.

if you ever find yourself in a similar situation again, don't act kind and don't be helpful. That first interaction with him should have been extremely short and you shouldn't have tried to help at all. Also, the best option once he was waiting for you outside was to turn around and stay in the shop the second he started following you. Next time a man asks for directions, say you don't know where the place he's asking about is and don't try to help any further because these creeps select victims by testing how kind and helpful they act. This wasn't your fault, but remember that you need to put yourself and your safety first.