The afterlife..

Do you believe in the afterlife? I'm not so sure.. I'd sound crazy to say I did, but then to say I didn't would be a lie to all I've experienced and to myself, and personally, I'm not much of a liar! I don't really wanna bring this up 'cause it'll probably just upset me, but as it's seriously bugging me and effecting me at the moment, I feel I must. Unfortunately my next door neighbor passed away earlier on this year.. And it's affected me dearly, however I knew that if I experienced anything weird I'd know what I believed about the afterlife.. I've experienced too much and I'm still not sure.. I've tried to use the excuse of "it's psychological" but every time it's been when I haven't been thinking about him.. So it can't be. Soon after his death, I smelled weed, and he was a heavy smoker of it.. I've smelled it a few times and every time it's been around me, it only ever happens to me, and I put that down to the fact that as a kid he was like the big brother I never had, he seriously looked after me and so to lose him had a really big effect on me.. God I'd love for an older brother, but like, quite a lot older than me.. Every night, after around 2am, I hear doors slamming next door, which was a nightly routine for him, there's always at least one door closing every night. Last night there were 2. So I didn't sleep much and just cried to myself. One night there was a door slam and then someone went thudding up the stairs, just like he used to, but luckily that's only happened once. And there was one night when I couldn't sleep again and I got thirsty so I went downstairs at around 4am to make myself a cup of hot chocolate and someone was arguing next door, like full on screaming at someone, just like he used to when he didn't get on with his dad, but there was only one voice, just arguing to itself.. That was probably the scariest situation yet. I have every reason to believe in the afterlife, but I just can't accept it I guess, and I don't know what will make me. What's it going to take to throw me over the edge? I wake up to find him watching over me? I don't know, christ if that happened I'd never sleep again.. Help, please?