I still don't know about Leanna, but I have some thoughts about "I'm doing this for you".
When my mom died, I decided that it was my job to be there and be strong for my dad. I helped make sure all the funeral arrangements were made, that everything was taken care of at the house, whatever needed to be done. I did not stop to let myself grieve at that time, because I wanted to make sure my dad got through it. Looking back, that was probably a mistake- I should have allowed myself to grieve while I was around my whole family. Instead I dumped it all on my husband later. But anyway-
At the point of the funeral, Leanna was in a weird place. She had just lost her son and her husband was in prison for it- her whole life had fallen apart. Maybe she just decided that she had to be strong and get through this, that she had to do it for both herself and Ross since he couldn't be there. It's easy for us, looking back, to judge this behavior as inappropriate and suspicious. But maybe, at the time, that was all she could think of to do. Maybe she had to steel herself to keep from falling apart, to hold onto the remnants of the family she had just days before.
Even at the PCH, I could see her wanting to hold it together, not to break down in public. Maybe her anger is even taking over at that point, hearing about the sexting (which she probably knew a little about, but certainly didn't want broadcasted for the whole world to know). Leanna at is probably feeling pretty embarrassed and stupid, and realizing that whatever shred of her former life she was trying to hold onto is gone. Whether or not Ross is guilty or found guilty, their marriage is over. I can see her feeling empty, hollow, void and emotionless.
I know there are a lot of other factors, I know. And really, I can explain and rationalize most of them. It's when you add them all up that it becomes really hard to accept all those individual explanations. I would like for her to be innocent, but it is going to be hard for me to believe that she is until we learn more.