Meant “leaves”. This is my favorite succulent and it’s been doing well for years. Any advice on what’s happening to it?  Disease?  Overwatering?

Indoors in a bright window. Has been in the same place for a long time though, so I don’t think that’s it. It was really cold recently though...  

Watered once a week. 

the edges of the leaves are disintegrating / turning grey and almost like ash

Can you maybe give more info? Indoors? Outdoors? Light? Water?

I see dark spots on background leaves. Could you have mealy bugs? They leave a scar on plants where they nibble.

Decaying leave