Is it normal to want out part 2

A while back I posted my story about my mother-in-law and my husband being the only child. She lived with us for 16 years and her wanting to move back with us. I gave my husband an ultimatum, she moves in, I move out and we are done. Difficult mother-in-law. One can only take so much. So she decides to come back, calls my husband one day that her friend kicked her out and she needed a plane ticket. He told her that she couldn't move back with us because of how she has been and that I would leave him. She lied to her son and told him that she had a place to stay and if he could just pick her up at the airport. The day arrives, he isn't answering his phone and it is now 8p.m. He finally answers and tells me that she has no where to go to. Why would she lie? Because her plan all along was to manipulate her son and in hopes that he would bring her home. I put my foot down after 16 years. She ends up at my sisters for the night to make matters worse. Never involve family, too late. I am mad at this point. He makes me feel bad and we start to argue for the next couple of days. When my mother-in-law left a year ago, we were in agreement that she couldn't move back with us. She would have to rent her apartment. What she told him, not sure, but I felt betrayed. He had promised me that everything would be okay and I felt so betrayed. We called it quits after 16 years of marriage and 3 kids. I was in shock and couldn't believe it. 2 weeks passed and we couldn't let go so we decided to try to work things out. She never moved in with us but found a lady to live with and help her and in return she would get paid. Great! It has been about 2 months and things haven't been easy. She still calls him and still wants to come back. I don't think she sees the whole picture. She caused so much pain. The kids saw what I went through and couldn't believe it. Things aren't the same with his mom and they never will be. He still feels pressured and I always worry. I love him but have many doubts as to it ever working out. He will never find anyone that will put up with his mom and he knows that. I know it is hard on him but I couldn't continue to live with her and was tired of being unhappy. If it weren't for his mom, we would be so happy. Every fight we have is always about his mom. She told everyone that I kicked her out and pretty much I am the bad one. I don't know what to do. Is it worth it? There are times that I honestly think, I am better of alone with my kids. And then other times, I tell myself that I have to fight for my happiness and she can't win. I can't understand how a mother can love their children so much and yet cause them so much pain at the same time. If she loves him so much, she should live her life, still being part of ours but know her boundaries.