My year 10 class are currently working on a Catullus assignment, so I've put together a list of some websites which have some helpful information.
Start at this site where you can read a bit about what we know of Catullus' life. There's also some information on themes to look out for when you are reading Catullus' poetry. The site makes the comment that most of what we know about Catullus' character and personality comes from his poems themselves. How does this website imagine his personality? How is that true from the poems you have read so far? The site also offers you the Latin text and translations in just about any language you could want. You can also read comments and discussions about the poems, or post your own if you're feeling brave.
Wikipedia has a bunch of information about Catullus, and some brief comments on poem 85.
Here you can find Catullus' love poems set out in chronological order, with a brief description of the circumstances in which they are thought to have been written, and here you can find some notes on tricky bits of translation.
For something a bit different you can visit this site, where you can listen to the poems being read aloud. There is also some background information to the poems.
If you find any other sites you think are helpful, you can write them in a comment below.