Not to sure how to feel about this..

I am currently in a long distance relationship with the absolute love of my life. He lives in Minnesota and I live in Canada and he drives up once every couple months to see me..everything has been great this past year and a half with him till now...He just recently decided to add me on Facebook and I couldn't help but creep which I'm sure most of you ladies do especially when it comes to your man lol but I came across an old picture of him being super close to this girl and I kind of questioned him about it, he said him and her were never together..so I was like okay..although I didn't believe it because she had captioned it so deeply in love with this man... I then decided to look on her profile and saw a status that she made about a month ago on his birthday. It said " Happy birthday to the best hubby in the world❤️love you Hun, hope you have a great day. I want to see you soon with a smiley..I have so many thoughts running through my head and my heart aches..I want to screen shot it so bad and ask about it but I don't want to come off as a psycho stalker girlfriend because that honestly isn't me...I'd also love to inbox her and cuss her the fuck out but I feel that would be to childish..

Not to sure what to do...