Karan is the best son and is truly tulsi's son, i think he will leave the house but not hate tulsi ever- he will understand the plan once he finds out that mandira is alive and then stay with mandira and spoil her plan (at least i hope that he will do that).
I am just wondering what mihir is going to do, now that he knows mandira is alive and kicking. There must be some reason why ekta has made mihir see mandira!