Is serequel XR a good medication to help treat severe depression with constant negative racing thoughts?

See below. Seroquel (quetiapine) (xr is the long acting version) has been found effective in treating depressive symptoms (like the ones you mentioned) either alone or along with other medications. Racing thoughts are often part of bipolar disorder, which is also treated with seroquel (quetiapine).
Metabolic syndrome. Make sure check your baseline blood sugar weight and lipid panel risk of metabolic syndrome it is approve for bipolar depression 6 more indications.