Thanks everyone for all the great comfort and advice.
He fired him yesterday, and it went better than expected. I have to admit, as psyco as he is, I was more than just a little worried it would become physical.
I feel extremly bad for his wife and kids...although I am angry at his wife, as well. Her co-dependency is a big part of the reason this is still going on. I feel bad for my in laws, who are super nice. My poor MIL is at her wits end...she knows that the wife is going to call and want to know all the details of why he was fired. Does she keep it professional and say he was fired for non productivity at work...or does she go into the tawdry details and perhaps end his marriage and let's face it; he will loose his kids....no doubt she will be able to get full custody. I go back and forth...one minute thinking it's really not her place to tell...the next thinking: hell, yes, the wife deserves to know everything. Can you imagine being faced with such a horrible situation at 76, with your 50 year old son...seesh.
I have not decided what to do about the job yet. DH and I actually met working together and worked together for a number of years...but it was a different company and I was charge. To be perfectly frank, I was much better at seperating home from work than he, so that does worry me.
I wish I could do part time and for a limited time...but anyone who has worked in sales, knows that really does not work. I was worried that the family would think DH was firing the brother to bring me in...but actually it was the in laws idea, I found out last night when my MIL called me...I worked for her before (she actually hired her son (DH) after I had been there about 6 months in the hopes we would hit it off...what a little matchmaker

Anyway, so she and FIL know what kind of worker / salesperson I am...that's why the want me to go clean up the mess...they know I can do it.
Financally, it would be great. Since, we live quite comfortable on DH's salary, we would put my salary 100% to the morgage, which would mean it would be paid off in 2-3 years.
Ack, sorry this turned out to be so long, again...just so much going through my head...not feeling very twinkly this morning :( It is only 6 here now, I have been up since 4, I am going to go back to bed and try to catch a few winks before I have to get everyone up and going. Thanks for listening and letting me vent.