My ex boyfriend had custody of my daughter from ages 5-13 she came to live with me because he got a new girlfriend and moved in with her leaving my daughter at home I just filed for custody back and child support, that made him angery and he said he was going to take me for support for when he had her... Can he do that ?

Probably not. In most places, an award of child support is not retroactive. This means that he can ony ask that you pay chid support in the future, and then only, of course, if he has the chid.

Were you paying child support when he had the child?

This will depend on local laws and courts. He might make the case, that he asked for no support for 8 years and now you get her and are asking for support.

While I don't think he will get back support, he might get the support you are awarded offset. Depends on the judge.

if there was a support order in place, yes he can. if there was not a support order, in some places yes, but other places no, it will depend on where he lives and here you lives.

Also what do you mean by Left her ?