Supporting DH and Family: Dealing with MH/Relationship Issues in Family

[Abrahamkin]

My MIL has suffered from MH issues for many many years. This has, of course, been very stressful for my DH's family, such that it has now gotten too much for my FIL/DH's father that he has left the marital house (this has been a long time coming). FIL had asked to come and stay with us and my DH said yes (which is support). MIL is now being admitted to hospital as she is, understandably, not dealing well with this.

Not sure what I am looking for, but I really want to be able to help my DH and his family get through this, however 'getting through this' might look. So maybe advice on how to support the different people involved, or even advice on what could be helpful to say and what I shouldn't say. If you have been in a similar situation, what has helped? What didn't help!