"Can we live comfortably without the illusion of freewill?"
This is a nonsensical question because without the illusion of freewill there is no 'I' and thus no 'we' to be comfortable or not. To destroy the illusion of freewill it would be necessary to destroy whatever mechanism it is that we perceive to be ones 'will'. Ones 'will' is best described as the thing which causes deliberate conscious action, we 'will' our hands to move and 'will' ourselves to run fast but don't 'will' our heart to beat (1). Thus to destroy one's 'will' would mean destroying the thing which allows us to perform deliberate conscious actions. As a result we would cease to eat/drink, since that requires deliberate conscious action, and would starve to death.
However, for the sake of argument let's ignore that problem and assume there is someway to remove the illusion or freewill without removing deliberate conscious action. Without the illusion of freewill then we would know that whatever we perceive as 'we' is an effect of our actions not the cause. Such an
acceptance would destroy our self-confidence and sense of self-worth. We can infer that self-confidence is important for our survival (probably by maintaining motivation) because numerous cognitive biases have evolved which preserve an inflate sense of self-worth despite evidence to the contrary. For instance, optimisim-bias causes >80% of the population to think they are above-average drivers and/or have above-average intelligence. Similarly confirmation-bias causes us to filter evidence to reinforce our existing beliefs thus causing us to believe we are right and that the evidence backs this up even when it doesn't.
We can extrapolate what would happen from such a complete devastation of self-esteem by considering the evidence from more minor issues such as bullying, and various forms of abuse. Generally, low self-esteem causes depression, anxiety, and stress. People with low self-esteem do not take care of themselves properly and may develop diseases such as obesity or malnutrition as a result. Some develop other psychological disorders (schizophrenia, psychosis, multiple-personality disorder). Many turn to illegal drugs to self-medicate. And far too many commit suicide. Thus even if we could break the illusion of freewill without destroying our conscious self and starving to death, it is likely most of us would commit suicide to escape the resulting depression.
(1) footnote: 'Will' is also used to describe things we wish to cause to happen
regardless of whether we actual do cause them to happen, eg. willing a
drowned child to live, but since such 'willing' has no effect on the
world it is irrelevant to the discussion at hand.
