It might be confession time, my brother.
From what I can tell, you have a friend who is an Alpha, but still has a caring heart and who obviously loves you very much. I would wager that he suspects you’re gay (if you haven’t told him that), and he probably senses that you’re submissive (judging by his comforting of you as children). So I think the stage is set for a confession in order to lay out the truth for him.
Here’s what I imagine. You tell him that you need to talk to him in private. When together, show him that this is difficult to discuss. Get down on your knees, head bowed and face to the floor. And then begin to confess that you are a faggot, that you’ve always been a faggot, and you have always felt the need to serve him. He might think you’re joking at first, but assure him that this is the most difficult thing you’ve ever done and you are totally serious.
At this point, he will want to talk to you about this. He might ask you to stand up or sit down rather than kneel. You do whatever you feel is most comfortable for you emotionally. But you cannot waver on this desire to serve him. You can even emphasize that it’s not necessarily a sexual thing, but rather a need you have to serve a superior Alpha like him.
Believe me, Alphas understand this much better than you realize.
What I’m proposing requires a lot of bravery on your part. However, I think you are safe with this Alpha. He might want further information on this subject, so be ready to either show him or send him information you can find here on Tumblr or elsewhere.
Be brave, my brother. Remember, you are helping him to understand a friend he cares about very much. But just as importantly, you will be free of this pressure and finally free to embrace the truth about yourself. You are not alone, and you are right where you need to be!