What to do about this guy I like

I'm 18 and made friends with a guy at my college. He's so sweet and funny and generous. He's also pretty popular. He does have autism which u think is why he hasn't picked up on how I'm feeling towards the situation going on right now. I've developed strong feelings for him and became close to him. I didn't know at first that he went both ways until I found out him and his best friend hook up. Well two weeks ago I told him I really like him and we ended up hooking up. And we started hanging out more and he would kiss me. But then when his best friend came around he would kiss him too and I saw a picture of them kissing at a concert. I didn't know how to feel because technically we weren't officially. We never asked each other out. He also never hid this from me. I tried talking to him and beat around the buff as if I didn't care and I jokingly ask if him and his friend hoon up often and he said yeah. I ask does he hook up with anyone else and he said "Before you, no. I'm demisexual so I have to have a close bond with someone before I can be intimate with them." I asked does that mean he loves him and he said yeah. I asked how he feels about me and he said "Well obviously I love you." He obviously wasn't picking up on what I was trying to get at and I didn't want to our right say it. I spoke to my mom and sister. My sister told me to straight up forget about him. My mom said he doesn't sound like a bad guy and since we aren't official and I haven't said my feelings that's probably why he doesn't understand that I want something monogamous and to just tell him that. I told her I don't want to make things awkward but she said the worst he can say is no. I really like this dude but am wondering if I should tell him my feelings and be straight forward or just leave it alone...