You should always want others to experience the happiness and joy of life. Even if we're talking about an ex spouse, and ex-girlfriend, or an ex-boyfriend. Although it isn't the easiest of things to do at times, it's something that you can truly benefit from. You should want the happiness of others even when they've hurt you, broken your heart, or found a new love that they're more compatible with.
Just because you and your ex didn't work out doesn't mean that you hold a grudge or wish them any bad will or feelings. To get to this stage of enlightenment is a big deal, because it will bring you more peace and happiness in life. When you're able to accept the fact that you and your ex are not together anymore, you're headed in the right direction. But the next step is to make peace with the fact that you've gone your separate ways, and be willing to give your light and love to them even from afar, knowing that they've moved on.
Wishing someone the best can be done in many ways without even having to say a word. Whether you're in communication with your ex, whether you're cordial or even if you've ended on bad terms, it's important to dive into the spiritual world and find a place deep within you where you can still wish them love, happiness, and an easy path in their life. When you get to this level of enlightenment, your journey in life and towards finding a new love of your own will be much greater.
Remember, even if your ex doesn't wish you the best, you can still take the highroad and wish them well regardless, because it just shows what kind of person you are. Just make sure that it's genuine. For your own well being and whether you have children with your ex or not, you should strive towards getting to the stage of enlightenment where you can truly wish happiness onto others, despite your past with them, and regardless of the circumstances.