I have a written agreement between myself and my X husband for coverage of rent anything over 1,000 dollars until the kids are 21 years of age and life time child support and alimony (my life time) with a 30 percent increase every two years even after the death of my X if I out live him. We both signed and dated it. My question is is it legal and years down the road could he fight it in court or will it stand up in court?