My only advice is DO NOT DATE OR BRING IN OTHER PEOPLE INTO A BROKEN MARRIAGE.
It isn't going to fix things.
Also dating as a couple is also not a good idea. Only in extremely rare cases does it work.
Read these links
40 yo straight female
Married in the eyes of the government to Butch since 2001...
Murf my monogamous second husband has been with me since May of 2012.
In a V relationship with an average 50/50 split of time between my two husbands.