Tinky, I have had enough crazy relatives to know how exhausting it is to deal with them, and I sympathize.
The only way I know to stay sane, is to focus on what you can control, taking responsibility for yourself and your own actions, and bringing the most mature and kind choices you can into the situation. That usually includes some honest self-examination of how you may be contributing to problems - even if you had no bad intent.
If you want hugs and sympathy only, that is what the hugs board is for. Advice boards are where people will ask you questions and challenge your take on the situation. Several folks here, myself included, think that there are things you could do - or stop doing- to improve the situation and make it (slightly) easier to deal with your inlaws. It's your choice whether you want to take that advice or not, but just re-iterating that your inlaws are horrible, selfish, controlling people really doesn't leave YOU anywhere to go, does it?
You can choose to treat selfish, controlling people in a kind way. You can choose not to make things worse. You can choose to give respect even if you aren't getting it back.
Best of luck to you.