just found out a guy from work has been texting my girlfriend and doing late night conversations with her. I confronted my girlfriend about and she says their just friends. I don't buy it. I think he has ulterior motives. I'm planning in sending a facebook message threatening him back off.

What do you think? Please help I have mild autism and this is my first girlfirend. Im so scared and don't know how to act. Im so angry right now I could smash everything.