I have no doubt you are feeling extremely fatigued and unwell but thinking you are going to die suggests the possibility of some sort of panic reaction. Taking an excess of some nutrient is not going to cause you to die, you need to recognise this as an overreaction and try to calm down. One possible reason for the reduction of your sensitivities following choline supplementation is stimulation of histamine removal via the enzyme NHMT. In other words you may have increased methionine production via the enzyme BHMT, this in turn increased SAMe production which is the methyl donor for NHMT and so the enzyme was better able to act on removal of accumulated histamine. If this is the case it suggests that prior to the choline, your methyl cycle was sluggish. There could be many reasons for this. Some SNP combinations could perhaps be making a contribution but it is highly unlikely that you have some genetic blockage that is having dire effects. There is a great deal of hysteria on the net about SNPs and I urge you to be far more sceptical than you appear to be about claims for what SNPs do and don't do. The vast majority of the SNPs which generate a lot of popular internet chatter have little or no effect though a few do indeed have small to moderate effects. Furthermore, many are common variants that millions of people live with without too much difficulty. Strangely, the usually rare SNPs that can have very serious effects do not seem to be the ones that have captured the popular imagination. As for why the choline no longer seems to be beneficial and indeed why you seem to be unwell despite stopping it, consider that in stimulating these pathways you might have placed increased demands on one or more vitamin or mineral cofactors and have now depleted them. Multiple pathways have now become sluggish. Unfortunately there is no easy answer to which - it is something you would need to determine by trial and error. There is a thread on refeeding syndrome which might perhaps give some insight into the depletion phenomenon. Folate and potassium are usually the first nutrients to be depleted in this model, minerals come later.