Instead of even considering jumping into something with an ex, again, by the way, for you both, how about having fun just being single, and friends?
It's a red flag, when people depend on others for happiness, and a bigger red flag, when they keep going back to exes for that happiness.
I think you both mistake intense feelings of attraction, for love and happiness. You can justify it any way you want,
My Ex didn't fill my heart with joy n happiness as he did so I wanted him back
But the fact is you have a lot to learn about your own feelings and how to deal with them.
Stay single, and learn about yourselves.