My ex-spouse constantly lies. What should I do?

Dear Dan,

My Ex and the father of my 5 year old son lies about everything. That is a huge part of why we split. He wants to see his son and I do not want to stand in the way but I can not trust him at all. He will tell me he needs to drop our son off at a certain time so he can go to work and then I will find out he wasn’t at work. I find it very difficult to let my son go with someone I can not trust. We have agreements about things like NOT SMOKING in the house while he is there and he does it anyway. When asked about it he tells me he doesn’t.

I am not sure if I am being too controlling or what but I hate this. He has a habit of dating girls that are 15 to 20 years younger than him and so I have asked him not to use our son to further these relationships that last about 3 months. He sends them video mail of our son telling them hi and so forth. I have also now asked that he not introduce him to these girls unless it is serious because there have been quite a few that my son has met and started to like and then they disappear from his life and I do not think that is healthily for him. Please help me figure out how to deal with all this because I am at a loss.

Thanks, Tired of Lies