How long does a DNA test take to get results?

My partner of nearly 13 years had an affair between Oct – Dec 2010. I found out in Dec 2010 and asked him to leave. We have 2 kids together 7 and 3. We werent married but sold a house in the summer of 2010 so he could start a business which he did in Nov 2010. The woman he has been seeing is an old ex and has 3 kids herself. I know that if he moves in with her, her kids get priority in the CSA’s eyes.

Just found out April 2011 that he now may also have a daughter in Germany who is 14 (he claims he just found out in Feb!!!) wondering where my kids come in in the pecking order now and how can I secure their future. I really need help with this its such a mess at the moment.

Also how long does DNA testing take? when should I tell my 7 year old he might have a half-sister?