You're situation sucks! So sorry you're having to live through all that.
First off: what does your doctor say about you episodes even though you're on meds to help that? Have they suggested other med options? I used to listen to the Pedestrian Polyamory podcast and one of the hosts was taking Zoloft and it not only made him manic, made him severely angry in some of those episodes. Then he tried Wellbutrin (sp?) and found that balanced him out sooooooo much better as in no more manic episodes, and the real "him" was back.
Not trying to be a doctor, just make sure yours is!
Second: You say your wife is doing nothing wrong however she's not helping/supporting you recover from doing what a spouse vows to do in marriage: help your spouse through illness! (sickness & health, anyone?) You want her to be happy; does she want that for you? Is she willing to do some things to help you be happy like you did opening up the marriage so she could be happy?
Seems she's in the really selfish phase of NRE and letting you take on the guilt of "pushing her away" due to your illness and med complications instead of helping you with your struggles, finding ways to help you feel more secure in the relationship is not not doing anything wrong. She says she doesn't have a lot of forgiveness? Excuse me?
In the podcast I referenced above the illness did take a huge toll on their relationship. They still could not come to terms with how much time and energy spent on each other vs other relationships. Under the not compatible meds with him; he kept telling her he wasn't getting enough, she wasn't doing enough (& she felt she was putting in the time and the commitment) so she finally felt that if he didn't like everything she was doing that he ultimately must not like her.
Hopefully your seeking therapeutic help and getting the meds balanced out sooner will keep your marriage on track. Keep being diligent, follow Magdlyn's sage suggestions, get you healthy.
Btw: How long is the separation expected to last? How's your son handling all this? Gotta be tough with ill dad trying his best & essentially absent mother with no "mommy" day to day responsibilities.
Sounds dreamy: She's got a new guy, NRE and lives alone? Yeah, she's got some classes & gets to study on her own time table and whim--while your home struggling to keep healthy and being a single FULL time dad? Ummm yeah; seems very unequal.