need to vent ..

I am 26 years old and I have been with my fiance for 6 years. we met online and have been together since we were 19. he is my best friend and was there for me when I was getting bullied big time. he is my first everything. I lost my virginity to him. we have had our ups and downs but it is worth it in the end.. we have been trying for a child for over 5 years now with no success. a few months ago I got this message from a girls friend saying he was dating her and asked if I was with him still.. they said he was sleeping with her unprotected and that she might be pregnant. she went to the cops on him for something else and when we talked to the cops they said they know her very well and that she is absolutely crazy . today the girl contacted him and sent a picture of an ultrasound and said it is his and was going to make him take a DNA test to get child support from him .. I feel so confused and not sure what to believe :(

thank you to anyone who took the time to read this .