My guess was right..even though Pritvi's entry is confirmed. The man behind all the threats is no other than Dilip according to today's episode (how Kripa connected the dots) it was obvious from his threats before that he wanted Kannan out of Angad's life at any cost, wanted Kripa back in as the fitted bahu for the family, and wanted to avenge the whole Avantika ordeal that made him a subordinate member in the family with limited access to the wealth that was once under his control and consequentially lost his son's love and trust.
If Angad finds out that Dilip is behind this it wont be good ofcourse but what is his real plan, does he want to frame some other family member (Kanan maybe) to make Angad hate her..? I guess he'd only find out if Kripa speaks up but she's bound by her promise to DADI 😡