If we look at the Emani incident and then the two examples of spoken word incidents that Snow refers to, then look at the bigger picture as you put it (ie she died and the actual concept that it was by her own hand was no suprise to Colin) , how else are we supposed to view it. Is the bigger picture, not also giving consideration to whether or not all components mentioned above were available to the jury at trial? How can the jury consider the bigger picture, if they weren't provided with it?
There was nothing more the jury needed to know of Sheila. It wasn't she who was on trial. I'm certain they'd have learned all that was considered necessary from the defence, but despite that, the jury made the decision to convict JB.
It's perfectly possible that, during disagreements, she'd threatened to take her own life -after all, hadn't she told Helen Grimster that she'd (at some, unspecified, time) contemplated suicide?- so reasonable for Colin to have drawn such a conclusion. I believe he changed his mind when he was told about the boys.