Just kinda need some advice

the mother of my children and i have been on and off for seven year i have made some mistakes and i take responsibility for that and truthfully im committed and loyal to her now a little back ground our daughter is terminally ill and this last year has been mostly off between use as to emotionally destress and stubborn actions and selfish behaviors but we love eachother we fight constantly and i need some advice i have trie d everything she is just a bitch for every little thing some days