Really really need advice!

I have a seven month old baby. My entire pregnancy and postpartum my husband would deny sex and anything intimate 99% of the time I initiated. During my pregnancy we went 6 months without it and he seemed to get worse about it and denied it more after we had our son. He started acting weird and spending full on hours in the bathroom a day on his phone and when I would ask him about it he would deny everything. Even when family would visit, they commented on how it seemed like he wasn’t helping me at all with the baby and chores. A few months ago, it came up that he admitted to looking up exes online and then a few nights later that he would be scrolling on Instagram and something inappropriate would come up and he would keep clicking and get stuck on a loop. (History included a coworkers pics). He said that it apparently all started when our son got admitted to the NICU for a few days (he was out within 2) and it was the stress of that that made him start. Ever since our son was born I needed help, really emotionally and he wasn’t there. We don’t have any family near us and we live in the area for his work and so I know no one and it’s extremely lonely. He said that he’s always loved me and thought I was beautiful and he doesn’t really know why he would deny intimacy with me. I found out a few months ago and this is almost constantly still bothering me. Just don’t really know what to do and need some advice. On a side note, we are just legally married but planning a religious ceremony to get our marriage valid in our religion. Having second thoughts on this. Do I back out??