Do stay strong, not because of yourself but also for your child, as you said this is so that he can progress at work and give you guys a better life.
You can consider creating small nuggets of time for you and your child to have with him. In our family, my husband always brushes my gal's teeth on weekend mornings and night. . Also, he puts her to bed every sat and sun night. These are their special bonding time and I don't intrude, I stay out of the bathroom and bedroom on these time. For myself, we always have a talk early in the morning before he goes to work.
Remember quality time spent is more important than having quantity!
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