Good morning TDG,
I am sorry you are having small issues with your BF but I am going to side on you are overreacting. I know you know how I feel about MySpace so there is no need for me to get into that one.
One thing that may or maybe be a factor is closure with his ex. Sometime when someone is taken away from us, either from a breakup or death, we have to either learn to deal with the NON closure of such a situation or we learn that we won't have an choice. We know in death it is at least final.
Regardless of the relationship or what it consisted of, he misses her. His actions can tell you that. So he posted some pictures on myspace. Why would this matter since he was there to pay his respects to someone he once loved? He is with you now. It's possible he is missing her in one way or another and just wanted to "see" her.
Maybe you could talk to him about her. It is possible that he could open up to you about what might be troubling him inside. Have you ever offered to go with him to the gravesite? This might show HIM you are woman enough to handle such a difficult situation not from a distance but beside him.
I know this may be difficult to understand but she may have been someone he loved just as much as you love him. I always try to put myself in other people's shoes in hopes of gaining a better understanding of how they feel instead of assuming or guessing.
I wouldn't let this bother you whatsoever. It merely sounds like he is having some issues letting go which is perfectly natural. Talk to him about it when you are alone sometime. I hope all is well and it's great to hear from you.