Im asking my husband to take a polygraph test for infidelity. Long story, but basic am I entitled to closure?

Its a long story but alot has happened to make me believe this has happened. We had a big talk, he wanted to part ways because of the "allegations"... which I just wanted to know why things happened. Anyway he said he wanted to be friends, but I wanted to mend the relationship which then I guess I was expected to drop it wholy. That is very difficult, and I am trying, we are getting councelling but not often unfortunately. So, I had a lapse of infidelity thoughts tonight, and I accidently mentioned to him I was planning on getting a lie detector test done to have my closure. He seemed keen on this idea, but all night has been really cranky, is cranky at the fact I havent "dropped" it all and doesnt know how he will feel after the test if he will want to be together. I am rather confused about all this?? I can understand his point that it has to go THAT far for me to believe him, but with his past record everyone, its really hard to sweep this under a rug. I have been doing so for my family for some time now. He also said if I would have not told him and just taken him there, he would have rejected the test. Later on, he started saying its a waste of money etc. Which, I disagree, and I found it odd that he was all for it, now trying to get out of it maybe? I dunno... any thoughts? thanks