Ok, So In Answer splitting up is a hard thing yes and it doesn’t always depend on how long you’ve been together but the situation does. The situation counts more than anything. In This Case An Affair. Yes, It’s Right To Leave,The reasons being this. You put his sexual health in danger by not being sexually protective yourself. Two an affair requires lies which are very hard to say to someone if you love them deeply. Three, It matters that a man knows if he’s a father, deciding to tell him as if he is, would cause extreme trauma not only to him when he finds out but to the child as well, now there is a possibility that he in fact would raise the child as his own but…The fact you have to ask and don’t know and your intent for the most part is lets be honest because I know no other way to be, your intent is to of had this affair and then continue a life with a man you’ve lied to,put at risk and betrayed. If you have some love for him don’t stay to take his stable financial life raising a child that isn’t his. Be honest with him,tell him everything, explain that he will have to be tested. You can tell him about the baby but don’t do it for sympathy. Do it so later if he see’s you he knows the truth that it’s not his. Be Honest, After 6 years, you owe him that.