What a horrible predicament.

Since you mentioned being on Lamictal: is your dx Bipolar? With MDD, you would be unlikely to take Lamictal. And if you have Bipolar, why haven't you tried antipsychotics? Many antipsychotics (APs) have been proven to offer antidepressant protection. Maybe with the right combo of an AP, Wellbutrin and Lamictal, you can survive weaning yourself off Lexapro and regain your ability to climax from sex.