Please help me with this conundrum!!?

i have been with my bf for 4 years, we have a flat and are v close, we have a bestie mate who hangs around with us basically everyday, he is 17 im 19. i never looked at him in a lust way and thought he felt the same about me, we get on very well as mates but that's it in my opinion! yesterday we were texting each other and i got a random text from his phone, 'claiming' to be from a friend of his (he's away at coledge atm) saying 'would i dump my bf for him as he talks about me all the time and is head over heels in love with me but doesn't want to tell me' i then got a text from the real friend saying that he didn't know what they had text, i forwarded him the text and he said 'oh sorry about that, they are nutters' it all just seems so fake! as if he text it and said it was his 'friend' lol in case i was horrified! maybe his friend did do it but i don't know. how should i approach this? i don't want to ignore it coz i don't want to give him any hints i might like him by accident if he did send it! HELP!!!! p.s i haven't told my bf and don't intend to