Do you know your kids may say that but honestly it's because they live with you a majority of the time so they see going to be with there dad the "fun" if they were living there constantly it owuld not be so fun, don't take it to heart it's the way many kids are.
There dad is probably having to do all sorts as he only sees them weekends, it's like when my dss comes to stay we go out & have loads of fun as we don't see him all the time & he does not live in our day to day life, so we make it special, he has said the exact words your kids have said to me but i know it's because it's all fun when he is here, day to day life, like school, baths, dinner, work,bed is not "fun" in kids eyes so when they get to go places with the other parent they think life will be like that all the time but reality is life isn't like that, there just kids they don't understand the daily grind.
Please honestly no matter what your kids say your there mother, they love you & without you there life would be full of pain, they need you.
You can get through this, just take one day at a time, your ad's may be the wrong ones for you, you need to get them changed, please phone someone hospital, doctor anyway if you talk to someone & get it all out if can help, there is other ways than just ending your life, your life will get better but at this point you can't see past the pain, these things take time & i promise things can work. x