Sorry but you are liable!.
You are supposed to take note of all posssible situations including the chance that someone may pull out in front of you and drive accordingly. This will almost certainly end up as a 50 /50 split. He could even change his story and say he pulled out and then you hit him from behind making it 100% your fault.
Just report it to the insurance and let them argue it out.
Eddie51 sorry your wrong he is not liable ,i'm a driving instructor (6 years).He was on the major rd with the right of way so the person in the side rd should have waited.
Yes you need to be aware of possible situations but if someone pullsout in front of you where they were previosly waiting and you havent got enough stopping distance.How the hell can you stop its not possible.
Problem is mambo44 if you hav'nt got witnesses you need pictures or police at scene. if you havnt got that, then as Eddie51 says he could say anything (literally).But you are in the right for sure.