Will the feeling go away?

It sounds like you only wanted her in a sexual way. You want him in a romantic way. So this is two different things. See if he can try and satisfy you sexually.

You might be addicted to the sex. Its common. So I guess that makes it normal.

the feeling never goes away me and my ex both have bf and gf and yet leave us alone we end up in bed faster then you can say sex :P

I think you have make a solid choice. If you want to remain faithful to your boyfriend you should probably be away from your ex.
Obviously your ex fulfilled a serious part of your life. However, keep in mind it is hard to find one person who will satisfy all parts of your personality. No one person will be "perfect".

If you decide to explore a 3-way be very careful. Be honest with all parties involved. Even then, others have told me someone always gets hurt eventually with 3-ways soooo.... it's up to you.
Your boyfriend initially might find it sexually very exciting, but may not feel comfortable after some time with the emotional connection you have with your ex. That could result in some bad fireworks. Good luck.

I think if you didn't have a lot of feelings for the girl you will eventually forget about her. You may think about her now and then but i think it will subside.

The feeling never really goes away, I still think about Ex's I had years later. Mostly because the sex with them was SOOO much better than the sex I am getting now.

But you could hint to your bf about you sleeping with your Ex. play it be ear and go from there...

You should have sex with your girlfriend while having sex with him. That will turn him on big time. Men love lesbian girls. I would do that.

Once things smoothen out with ur bf the feeling for ur ex will fade away..n its normal to have sexual feelings for ur ex

....... How the helll do you have sex with another girl?! Dont get me wrong, im totally fine with bisexual-ness and even have a friend who is bi. but i never really got how they worked it out...... in the bed i mean