My sister-in-law ruins Christmas?

You say she seems sad and does her best to disguise it? She sounds like she's trying her best NOT to ruin Christmas for you. She probably has clinical depression, which usually gets much worse around the holidays, no matter what you do to avoid it. It's not something you can snap out of, believe me. I know.

It sounds like you're overreacting to her moods. Maybe you should see a therapist so you can get all this hostility off your chest without involving your OH. Christmas can be hard on everybody.

Don't allow her sadness to affect the day. Her sadness might not be personal. Christmas time in general might contain sad memories for her. Enjoy the day with everyone and if you do get a spare mo then perhaps have a friendly chat with her to see if you can understand why she should act this way at Christmas time. She might welcome the opportunity to talk about it.

Merry Christmas!

The poor sad lady is doing her best. She isn't doing anything wrong. Just get on and enjoy your christmas. What more can she do? Why allow the 'sad' aura to affect you?

Just play some Christmas music, watch Christmas movies and drink some alcohol.

She ought to have subject matters. i assume that because she is spending christmas with you she has no man or woman else. the concept-about that makes me somewhat unhappy. possibly you and her must have some beverages, get her merry! possibly she's lonely, possibly she is jealous that she don't have what you and your different 0.5 have. possibly she's satisfied for you both and shows that happiness yet deep down interior wonders why she will't have that exact same happiness. only a theory.

It sounds horrid, but just get on with your Christmas - if she doesn't chose to join in , leave her be. Its YOUR family Christmas - HER problem if she decides to be difficult.

And perhaps make a mental note to ask your other half to explain fully in the new year JUST what her problem is, so that you are able to understand what she is going through and how you can help.

You can't make her better, so don't try, focus on the family members that make you happy.

Meet, greet.. say goodbye and leave her to talk to others, or just sit and watch you don't have to bring her into every conversation. She might just not like to participate but wants to watch while others do, many people are like that, so leave her to do her own thing.

Show some empathy - this lady is probably depressed! It is important for her to be out in company! Your mood should not be affected by hers!

it's just one day..let her have it and be glad she's not criticising you or looking disapprovingly at you like my bf's family do to me

Get drunk.