i am confused

If she is seeing another man, that means she don't love you anymore. Maybe she is waiting for you break up with her.

No you should not because shes been unfaithful. Thats the only reason you need. If you two were to get married it would be very likely that she will cheat on you. Based on that you have had a 10 year relationship you need to know why she is cheating on you. Ask her, pressure her,and do not let up until you have an answer.

Ten years is a long time but sometimes you just need to know when to let go. If she's with someone else leave her let her be. Because if she's acting this way I don't foresee her trying to change her ways anytime soon. Should you still love her?? You're always gonna love her, the question is should you stay with her and to that I say no. No matter how many years you're with someone, cheating should not be tolerated in any way,form or fashion.

it depends on you if you can take the fact the she has not been faithful to you. but hey, is she supposed to be faithful when you guys are still dating yet? are you guys into a serious relationship now? because if you guys are, then maybe you have the right to get jealous of the boys that surround her.

We cannot control your love towards that girl, but we can suggest on what you can do. I suggest that you stop seeing or dating that girl. If you don't, you'll just keep hurting yourself. What's more is that you have been dating her for ten years! Always remember that there's always a limit to what you can endure. I hope you think these things through, especially since it's a serious matter. I wish you all the best.