AIO for divorcing my husband

I 30(f) have been married for 2 yrs but together a total of 6. Last year around this time I found out he had been cheating on me with multiple women and he got one of those women pregnant. The child is 6 months younger than our oldest .

He’s trying to convince me that it doesn’t matter because it was before we got married.

I already started the process just curious on how others would think/ handle the betrayal

I just cannot wrap my head around any of this & I hate that I’m ruining my family but I just can’t get over it.