Urgent mental issue. To see you asap?

I have a relative who is highly suspicious in nature. She believes that the husband is having another ex marital affair. She keeps shouting throughout the day and pushes  the other person to confess by force to things which might not be true. Recently one diagnosis of her situation said that she is suffering from delusional infidelity. She is Highly resistant to medication and in constant denial to understand to other people's suggestions. At times and at odd hours she gets aggressive and start attacking the other person through verbal or sometimes physically with constant verbal confrontation. Please suggest what can be done in this situation. How do I convince them to take the medication or shud I come down to see you asap