For the OP -- your tiers in this "V" polyship.
You must learn and understand the tiers in your polymath.
Each mini relationship inside the larger polyship needs TLC for the polyship to fly right. Or else it all folds like a house of cards. If one tier is NOT in right relationship to each other, then the polyship as a whole is not in full right relationship. You WILL feel the trickle effect.
In this situation you have SEVERAL layers not in right relationship. Straighten yourselves out on each tier and make the apologies and repairs each tier needs to have.
CAST OF PLAYER
you (the husband)
you to you (your relationship to yourself as part of a V. This is different than you to yourself as just a husband, or as a footloose single. Now you have others to think of because you actions affect them.
wife to wife
GF to GF
you --> wife (can you go to her with your stuff well? The arrow points to her.)
you --> GF
Wife --> you (does she come to you with her stuff well?
wife --> gf
gf --> you (as her metamour and maybe also a friend NOT lover)
gf --> gf
you <--> (wife + gf as a couple) [saving space, relationship info arrow flows both ways. You relating to them as a couple and giving them couple space and consideration of their feelings as a couple and couple needs. The couple relating to you and giving you space and consideration of your feelings and needs.]
wife <--> (you + gf as metamours)
gf < --> (you + wife as marrieds)
you + wife + gf (functioning well as a V shaped polyship with wife as the hinge. Communicating as a trio, calendar, family meetings to address what is going well and what is not, hanging out together, etc.)
How you want to be when this ends. All relationship come to an end. Talk about how you want to be when it ends. Part as friends? What?