ADHD Help

Hello everyone, my boyfriends daughter is 5 years old and has ADHD. She throws horrible tantrums and lately she has been waking up a lot during the night and not going back to bed. Learning trouble, and her father and I have talked about having her take the medication to help her some. Lately, when she is uncontrollably crying and screaming and talking back I put her in time out and usually it works. I am normally with her more then anyone else, and can see she is going down hill, but when I try to bring it up to her father he tells me that I need medication and I should let him parent. I'm sorry, but it's just not acceptable for him to tell me that. Then he gets mad because I feel like I should go to my dads and cool off, like I'm the bad one. All I care is that she gets the help she needs, but anytime I say anything he jumps down my throat and tells me there is something wrong with me and not her. I don't know what to think. Opinions?