Most Helpful Guy
I think it's okay to be jealous, it shows that you still have some kind of feeling that is linked to that person and there is no helping that emotion when you see them.
You don't deserve punishment for being jealous but I can only suggest that you don't let Jealousy interfere with your daily life but rather try and adapt or get over it.
I have been jealous of peoples relationships with people I liked but I managed to deal with it and even though I am jealous I don't hate myself for that and neither do people punish or judge me for being jealous.
Hang in there :)