Continuing the discussion of bitachon, one of the questions I left off with is how to square the idea of bitachon with shema yigrom hacheit. If a response to true bitachon is promised even to the unworthy, then of what consequence is the fact that one might have sinned?
With respect to Ya'akov's fear of encountering Eisav because of shema yigrom hacheit one can possibly kvetch and say that Hashem might have responded to Ya'akov's bitachon my sparing only Ya'akov, or Ya'akov and children but none of his property. This answer addresses the "letter of the law" but I don't think it addresses the spirit of bitachon. From Hashem's perspective there is no difference between saving all or saving part; once bitachon is in place, why not trust that Hashem will save all? The Ramban suggests this kvetch, but also pulls no punches and writes that perhaps Ya'akov's fear of shema yigrom hacheit was in fact a lack of bitachon. "Lo kol hama'amin boteach." This same idea is echoed by the Rambam in Shmoneh Prakim who proves from this episode that a Navi can have failings (see R' Elchanan Wasserman's explanation of this Rambam at the end of Koveitz He'oros. I don't see his question.)
A lomdishe answer to this issue is given by the Alter of Navardhok in his Madreigas haAdam. The Alter writes that the reason for Ya'akov's fear goes back to the brachos given by Yitzchak. Ya'akov was not blessed with unconditional dominion over Eisav --Eisav received his own blessing guaranteeing that when Ya'akov let down his guard and was not observant of Torah and mitzvos, he, Eisav, would be able to rise against Ya'akov. The fear of Ya'akov was not because G-d does not respond to the bitachon of a rasha, but rather because Hashem would fulfill this bracha to Eisav if Ya'akov did not measure up in tzidkus.
I would simplify this answer, and by coincidence, this brings us to this week's parsha : ) The Ohr HaChaim asks what Reuvain was thinking when he suggested lowering Yosef into a pit filled with scorpions rather than allow the brothers themselves to harm Yosef. Either way, Yosef was in danger, so what was Reuvain hoping to accomplish? The Ohr haChaim answers that scorpions and snakes have no bechira and could harm Yosef only if Hashem decreed such. However, the brothers had bechira. Hashem allows bechira to play out even if it goes agains the ideal Divine plan.
It is one thing to have bitachon that one will survive and illness, a dangerous storm, etc. In these cases one faces the threat of nature, which is completely controlled by Hashem. It is quite another thing to have bitachon from another person's threat, as Ya'akov faced in his encounter with Eisav. In this case Hashem's promise to intercede on behalf of the ba'al bitachon is overridden by Hashem's desire to allow the free will of people to play out in this world.