Lots of posters jumping straight to "give the baby formula".
Personally I think the problem here isn't the breastfeeding. OP has five children, I'm assuming she has breastfed before and is/was aware of the immense commitment this brings, but at 8 months that intensity will be starting to lift, baby will be weaning on to solids, and will start to feed less frequently.
Yes giving bottles gives the option of someone else feeding some of the time, but hubby is at the gym till all hours. So if OP is going to be doing the feeds anyway what benefit does formula bring?
Add into it that she presumably has chosen to breastfeed, and had she wanted the baby to be bottle fed she would have done so. Swapping to formula now, based on her OHs behaviour, would probably lead to feelings of regret or resentment further down the line as she would have given up b/f based on the poor behaviour of her OH, not because she felt it was the best thing for her or the baby...
So, I've gone a bit round the houses, but as I said, the breastfeeding isn't the issue. The husband and his behaviour is the issue... No?
OP, you say you have low self esteem, and the only thing you feel you are good at is being a mum. Well let me tell you, you are doing an amazing job. To have five children, the youngest a baby, still breastfeeding him at 8 months, you are smashing it. You've achieved massive things here.
And the fact that you have a baby who wants the breast for comfort, looks for it in the night, is happiest when he is in your bed, and is upset when with others (daddy at the moment) shows he has such an amazing bond and attachments with you, and this is such a positive thing for your baby's development. This stage will pass, and he will be happier with other people. My children were exactly the same, but by 11 months I was leaving my youngest with daddy twice a week while I was gone for 14 hours working shifts. A few months earlier that would have been totally unachievable... It gets easier, hang in there.
Don't jump to sacrifice the hard work you've done with the baby. Work on the real issues, the ones you have with your husband xx