Is it time to kill myself yet?

So pi-/+ almost exclusively decay to muon -/+ and a (anti) neutrino, it also decays to e -/+ and (anti) neutrino but at a much lower rate (about 10,000 times lower). The pion is spin zero, so the spins of the lepton (the muon or the electron) and the spin of the neutrino must be opposite so that their spins add to zero (conservation of angular momentum). In the pion's rest frame the neutrino and lepton must also have back to back linear momenta (conservation of linear momentum). The pion decay is mediated by the W-/+ boson, which means it is weak decay so it only couples to fields with left chirality. For ease of description we'll consider a lepton an anti-neutrino and consider the anti-neutrino to be massless. A massless anti-particle with left chirality is right handed means which means the momentum and spin point in the same direction and a massless particle with left chirality is left handed means the momentum and spin point in opposite directions. This means if both the lepton and the anti-neutrino were massless and had opposite linear momentum then their spins would have to point in the same direction, but we know that they must point in opposite directions to conserve angular momentum (since the pion is a spin zero particle). The heavier the particle the easier it is to move away from left charility means left handed, so that means the lighter the lepton the more suppressed the decay will be. The muon is about 200 times the mass of the electron, and it likelihood of decaying through either channel is roughly proportional to the mass of the lepton squared. 200^2 is huge, so the muon decay is much more likely.