Should I Take It Serious?

So my ex and I dated for 8 months or so but knew each other for almost 3-4 years. We split apart for about 6 months or so and we both went to other people during that time but we started speaking and might get things rolling again . I’m afraid she’s still speaking to the girl she was with while we were broken up. Or that the same thing might just happen again so is it wrong if I “date” (as in hang out with other people no kissing or any extra stuff) around just in case she’s not in the same mind set as me ?