Soo miserable

I've been married for one year already with my classmate (we are togetger for 7 years now). We got some troubles in relationships, ttc and have no results yet. Occasionally, I met a guy, who has everything that I ever needed (he is mature, confident, caring etc.). Things got harder, because I feel, that I'm not unneed person anymore and want to try to stop my relations and have another one. But, for three days already I have strange feeling in my pelvic area, like somebody is trying to squeeze my organs and have medium brown spotting, like before my period (period is due on Sunday). I am wondering if it's the first sign of pregnancy or not. Really hope it's not, because I now understand I won't be happy woman with my husband.:(