She may end up contacting me. I don't know how I am going to handle it. I don't know how I should handle it.
Do you guys have any tips?
What can prevent me from getting sucked in?
plain and simple: don't answer that phone call (or email or text) or whatever way she attempts to contact you
how do you know she split with the new guy? are you keeping tabs on her via social media? do you see her out and about?
if you really want nothing to do with this person, eliminate all the ways she can contact you... .