Texas Based Situation

I live in North Texas. My Ex-Wife lives 100 miles away. I pay my Child Support on time and have for the whole time. Everytime I turn around she keeps making up new obsticles. The school where my Son attends don't contact me when he is absent. He is 7 and Daughter is 4. The Mother-Inlaw lives about 10 miles away. I have always been nice and tried to get along with the overall situation. But, it seems that my Ex-Wife thinks she can just go behind my back and do what she wants to with the kids. We are in joint but she is the primary. First we had a good agreement then it just kept changing all the time. NOw... she says kids cant stay at my house because i don't have seperate rooms. Then a buddy of mine who is a Father himself moved in cause he has came back to Texas and Ex-Wife says. Well, you don't have enough rooms for the kids and you have someone living there with you. It's a Man! She isn't married and been living with a man for about two years now. They have multiple people living in the house. But, I'm never told when they go to the gmaws. She pretty much tells me when i am going to see the kids. The kids were at their Gmaws for 3 weeks and I got to visit with them from am/pm. She brought them and picked them up and charged me for the gas to do so and Ex-Wife..not the court.... was telling me they couldn't stay over night. I couldn't bath them....a lot of stuff that didn't make sense to me. And just this past friday without telling me or informing me