I’m in the closet and need help!!

As you can tell from the title I’m still in the closet but I’m at the point now where I want to start to explore my sexuality. I have a few really close friends that would 100% be supportive of me we’re I to come out but there’s a few problems relating to a particular friend (I’m madly in love with him). We have a very open relationship and we’re not afraid to touch each other in an intimate sort of manner but I never do it to gain pleasure etc. We’re just really close and it’s just a joke, for him at least. If I was to come out to anyone it would be this friends as he’s the one who’s helped me through a lot of things in the past/ present. But my worry is that coming out to this friend will damage our friendship and/ or end it. Being in the closet has also affected my mental health as I feel like I’ll never have anyone to come out to. I would also like to explore my sexuality as there are no guys at my school that are out and I’d just like to know the feeling of an intimate relationship. Any support is appreciated.