Your concerns are valid, sinking! Perhaps telling him right out of the blue is not the wisest choice. I'd suggest to start talk about yourself gradually. You can decide yourself where to start from. You can make up some excuse for your absence at the beginning, by saying that you've been "sick" or anything similar and start to see how things are going for you. If you feel comfortable around him and it seems like a trustworthy person you can start revealing some of these things to him. I'd say that's the best thing to do in my opinion. However perhaps you'll feel comfortable by being honest from the beginning! Whathever works for you! Just start to reveal bits and pieces here and there. If he truly cares, he'll stick by your side and will accept you for who you are! If he doesn't, no harm done. At least you were honest and it didn't become anything too serious. Let us know how it goes! Sending many safe, warm hugs to you, sinking, my dear, sweet friend!