***Is my boyfriend cheating on me or am i being parenoid?***?

i have been with my bf for 6 years this coming august. i am 25 years old and he is 23. we had our ups and downs, broke up 4 times in the past 6 years. my bf has this friend and he hangs with him like 3 times a week. my bf friend has my phone number in his phone because my phone number is exactly the same as my bf except for the last number, and my bf happen to call me from his phone one time when his phone died. what i feel is very strange is how my bf friend kept my number in his phone. one day my bf friend called me and said hi, and i said hi back i had my bf number saved to my phone just incase i needed to get intouch with my bf one day. and i was like sergio? he said yeah, i think i love you. i was like what! he didnt say anything and i said hello! and he hung up on me. so i called him back and he said hello, i said hello, what happened? he said oh sorry i meant to call chris which is my bf. i said ok. then when i hung up i thought it was wierd why would he say he thinks he loves my bf? I called my bf and told him and he thought it was a joke, and didnt seem to care. so any way my bf friend bought a motorcycle to go riding with my bf cuz he has one too. and hes been bringing him to clubs during the week and he satys out till 3am and he's being sneaky about stuff. my bf lies to me and doesnt act the same when he hangs with his friend. i think his friend is trying to brake us up so he can try to be with me, before i met my bf he stole his friends girl from him. so i think he might be doing this to get him back even though its the past. my bf did this last nite and im getting tired of it. this morning i woke up and felt a wierd felling in my stomach like somthing bad happened lastnite with my bf. i think he might have went to a strip club. to me it seems like he's trying to live the single life, but duh, hes been with me for 6 years, hes in a realationship. i cant shake the feeling. do you think im being parinoid or do you think he is cheating on me.