hahahahahahaha I just spit my dr. pepper all over my rug hahahaha. Why don’t you just say look I met someone else, no I havn’t cheated on you but the thought has been in my head and I don’t feel it’s fair to stay with you when my heart isn’t in the right place. Use the whole “you deserve better” line, see if that works.
If your not happy with her, just be honest.