Should I stay or should I go?

I am 37 and single. I've been married before and have had several healthy relationships. 6 months ago, I reconnected with a friend from high school that I never really thought of as someone I'd be attracted to. We talked every single day through text messages, and after 2 months we decided to meet up. He lives 13 hours away but his parents still live in Florida so when he came home, we ended up spending time together and are very, very attracted to each other. After the initial meeting, we continued our text message flirting and then we met up again in July. We have become physically intimate with each other now, and there was a definite chemistry there. It's not just physical though. We talk about everything under the sun and reminisce about our younger days. Not that we're that old. Ha!

Here's where I don't know what to do. The text messages from him have slowed down. I see myself initiating contact with him more and more and he with me less and less. I asked him about it a few times, and he always has an excuse. His most recent excuses have been "I've got a lot going on" or "I just get this way sometimes because of my depression." I completely empathize with someone battling mental health issues but I don't know if that's just a convenient excuse? I might add that he has asperger's, so I don't know if that might factor in. To add to the confusion, often on weekends we text each other while drinking alcohol and he will say things about how crazy he is about me and that I'm always on his mind. He says that he's afraid to say those things when we're sober. I just don't know whether I should stop texting him or send him another text to ask him where I stand? I know the message will likely be the same. I don't want to lose any part of what we have, but especially not his friendship.