As Will said: Don’t worry!

How we behave also depends on the person we are with: If your partner reacts in a reassuring and comforting way when you get jealous it might just go away. But this guy just messed with your head. Whether he actually cheated or not: he did not behave in a very trustworthy way, and played his part to make you jealous.
So, in a relationship where there is trust you might be a completely different person!

And: We all have the need for some external validation, a great part of our perception of reality relies on it! So there is nothing bad about it! Take it and be happy about it, it shows you that your feelings were on spot!