Haliburton needs to learn to take the high road at this point. The Kings made a decision, because they viewed a Fox-Haliburton backcourt never working out, because both need the ball in their hands to reach their full potential.
In a sense, seeing how Fox has flourished after Haliburton was traded and getting back full reigns of the team, I don't think you can say the Kings made the wrong decision. Haliburton will go on to have a fine career too, he just needs to move on. Playing the scorned ex has a bad look.
I think this trade will go down as a Win-Win for both sides, Haliburton just needs to accept that and move on, you don't see Domas bad mouthing the Pacers for trading him and he's a young 2 time all-star. That shows the maturity of Domas in this situation.