i dont know what to do.

Names changed for privacy reasons. 

You don't feel guilty about being getting with your brother best friends, that's just an excuse for I don't really like you enough or I'm not really ready for a relationship with you.  More likely the first option. 

so we did end it. 2 weeks later, me and fred ended up alone at his place, so we started to make out again, and he maturbated me.

He's using you for sex.  He's not interested in a serious relationship but knows he can call on you for a bit of fun.  At least he's satisfying you by masturbating you, rather than just having everything for himself. 

after 4 days, i slept over at their place, and he sneaked in to where i was sleeping, and he started to masturbate me and eat me out. but i didnt give him an oral sex because i find it disgusting. so the next day, he ended it again, because he felt guilty.

Yes, he feels guilty because he wants to take advantage of the fact you fancy him and experiment with your body sexually.  Again, it's good that he's satisfying you and not forcing you into having oral sex with him.  But really he's using you as his play thing, he's not interested in you from a relationship point of view.  And that's why he keeps saying he feels guilty.  And he's worried your brother will find out and will beat him up, probably as well.

(just to mention, we used to text and call everyday during this period of time) he was my date for my prom, so that night we just kissed, nothing else. two weeks later, we were alone in the car, so he started to kiss me, and i told him that we cannot do this because he mean so much to me, and he said you too but when you start something it is hard to end it. so we continued to make out. since then everytime we are alone we make out, nothing more, but we do not call one another or text.

That's because it's only about sex, there's no relationship involved.  He's taking advantage of the fact you are hooked on him, he's giving you good sex but doesn't want any other committment to you. 

2days ago, we were alone, and we were making out, so i asked him that aside from temptation is there anything else involved? and he said he has no answer for me. so i told him that i assume it's a "no",

You are right, you know that he doesn't want to say no, because he knows you won't want to hear that, but if he was truthful, the answer would be "no". 

and he replied, "i didnt say anything".

He doesn't want to stop these sex sessions.  He really enjoys playing with you and experimenting, but really doesn't want the committment of having to take you out or spend money on you or have to communicate with you on a regular basis.  Guys typically get past the casual sex stage and look for a long term relationship when they reach 25, but some earlier at the age of 21, not a big percentage want a long term relationship before 21.

he has told me during this time, that he feels so comfortable with me, im amazing, i act older than my age ( im 17 and he is 23),

With that age range, he really should see you as very attractive for future potential.  Yes, he probably won't like your immaturity now, even though you do act older, but in future years he will know you will develop more maturity. You may act older, but it will still be really obvious to an older guy, you are young and impressionable.

he likes me alot as a friend. now he is kind of pretending like nothing has happened, but we havent been alone with one another yet.

i want to know if he has feelings for me, because I'm doing sexual things with him because i have feelings for him, i dunno if he is doing it because he has feelings for me aswell or he is doing it just for fun?

I would  say he only sees you as a bit of fun at the moment.  In the future he might warm to you from a relationship point of view but really I see this as less likely because of the way he's treating you now.

since i just gave him a hand job and nothing more, but he masturbated me and eaten me out.

he is very popular and he gets attention from so many girls. no one knows about us. he had sex with so many girls,

So really, he's just playing around with many girls and enjoying having women running after him.  He's got so many girls on a go, he's not really interested in settling down with any one of them. 

and since im a virgin, and i been sex after marriage , im not going furthur with him, i just want to knw if he has feelings for me, and i dont want to have a relationship with him, because i know it is not possible since he is my best friends brother,

To be honest I don't see why it's not possible to have a relationship with your best friends brother.  I think he's just used this as an excuse to keep things quiet. 

and my brother's best friend and he is 5 years older than me.

Again, 5 years older is nothing.  Some women even go up to 10 years older. 

I would say, more than likely he doesn't have any feelings for you at the moment.  He just wants to have sex with you and all the other women, without having to commit himself to any kind of relationship.