It's tough because this kid is a living embodiment of your partner's infidelity at worst (if he did this while you were dating) or to a lesser degree, his not being open with you about something so important.

I don't think you should beat yourself up because you don't feel you can love another person's child but if you don't feel like you can be kind to this child, then I might suggest that this is not the right situation.  It's not the kid's fault that his dad not only created him... but is also not doing a great job of raising him (annoyances etc).

But don't feel bad because even though I care greatly for my two SD's.. I am positive that if I had a child of my own that I would feel differently for a bio than a skid.  Not that I would like my SD's less than I do now.. but that i would likely love the bio more. (no possibility of kids for me though..lol)

You've forgiven your boyfriend because you love him, but hate the child for existing. I suppose it's natural to dislike the circumstances this little one arrived into the world.... but none of it is on the little guy. 

Your boyfriend lied to you. Ok, even went so far as to play you for the fool. I get that. It would be very hurtful. I know there is not one excuse the man could have come up with that would have made me 'forgive' him for lying through his teeth. He told you there was absolutely 0% chance this baby was his. Surprise, I lied. The man betrayed your trust in him. 

You say seeing the child reminds you of this lie. But this little guy does exist and the man did lie to you. Nothing can change that. Why hate an innocent child , but forgive the guy who played you for the fool? Why did you finally learn of the baby's DNA? Well that would be because the child has a legal right to be supported by his biological father. Had it not been for this child's rights (and probably BM having to declare and prove who the father was so she could get govt. assistance) this guy would have never came clean to you. 

Have you spent the last five years wondering what else he has lied about or is still lying about? Maybe, maybe not as you're still with him. I didn't read all the replies, have you tried seeking counseling for yourself? It might help you sort out your feelings and either decide to move on or to actually indeed forgive. Hating a child , especially one who has done nothing and isn't going to go away, could be extremely stressful and detrimental to your overall health and well being. Eighteen years to begin with and then college and the child's beginning of his own family and grandchildren. 

It's a long long road ahead of you. I'm not saying you must open your heart to this child, but it may be beneficial for your own sake to come to terms that this child as a human being has done nothing to you nor is the little guy in any way to blame for his father's stupidity and lies. 

Well I have to give you props for staying with someone for 6 years after knowing the huge lie he told you and you have never forgiven him.  This makes it extremely hard to trust him I imagine.

Sounds like you want to leave now.  Are you not still in love with him since tht is the reason you didn't leave in the first place?