Credulo, how about getting yourself a pen and paper and sit down and write what you would say to him if he were sitting in front of you right now.
Think of the reasons why you love him and include these, then think of the reasons that things aren't quite right at the moment.
Then read it back to yourself. How does it sound? too long? too short? a bit blunt? or too wishy-washy? and then cross out the bits that you think don't need to be in there.
As with all relationship questions on here, only you know the person - so have a try that way first, then come back to the post if you need help editing it. Having time to really think of what you want to say to him could help to clear your mind and de-stress you too.
All the best :-)