If we both want a divorce do I still bring proof of his infidelity

I was hospitalized for 4 months during this time my husband was rekindling an old flam with his ex. When I got out of the hospital he left me I later found out he was seeing her. Now he is planing on moving in with her but still hasn't gotten a divorce so now I have to and I have to pay for all this money which is unfair I found Facebook proof of his infidelity and his profile is public not private