My former employer sent a letter stating I could receive a lump sum pension payment in 43 and disabled will receiving this money affect my disability?

If the benefits you receive are Social Security Disability Insurance benefits, the pension payment would not affect your monthly benefits. If the disability benefits you receive are for Supplemental Security Income (SSI), the pension payment must be reported to SSA and will affect your monthly benefit.  For how long depends on the size of the lump sum benefit.