discouraged mommy

I've been exclusively breastfeeding since my baby was born. 

She's now 5 weeks and I just don't know if I can keep going... 

my nipples hurt like crazy, watching what I eat and limiting myself to girls nights is really catching up to me. 

I chose to breastfeed for the bond it creates and all the good things that come from breast milk. I do pump and she took her first bottle yesterday but I just feel as though formula would be easier ... 

see, things with my partner aren't going thebet, and I have been thinking of leaving and going for full custody ( I don't really want to get into it..) anyways, so I haven't switched to formula for that reason - he can't just take our daughter and leave with her since she's only breastfed. But I don't know how much longer I can take breastfeeding ... please ladies, I need words  of encouragement and advice.