Emotion is perception based - relative to memory and the result of the contact-feeling combination. Perception is basically awareness of an object's distinctive marks (one perceives blue, yellow, etc.). If, in repeated perception of an object, these marks are recognized, then perception functions as memory. Emotion is built on the collective "distinctive marks" of our experience. We remember the marks of "stick" and "for walking" and "other values." The variance of "other values" means the sight of a walking stick can bring forth, for one person, painful emotions (memories of being hit) and for another person, loving memories of a grandparent. Same stick - different feelings and different emotions. Feeling is always singular. In this second case, pleasant. Whereas emotion can be multiple: love or joy or happiness or contentment or ... there are many possibilities and many, many degrees for emotion. There is however, no such thing as "mixed feelings."

Feeling is one of the five khandhas (vedana-khandha) and as such is an integral part of being alive as a human being. Emotion is part of sankhara-khandha so is also part of our ongoing experience.
Although vedana is a distinct element of experience it requires a very still and spacious mind to observe a single feeling. The supporting conditions for that feeling are inconstant so the life of what we might call 'one feeling unit' is quite brief. Consider instead observing the mood associated with contact - the prevailing atmosphere of the mind. Language limits crisp distinction but consider mood as: spirit, disposition, temperament, flavour (of mind) and allow that it has less dynamic energy than does emotion. In the recipe of life feelings (moods) are the basic ingredients - emotions are the meals on the table. Ingredients can go in many directions - soup, stew, roast... Meals only have one option - consumption.

Consider that almost all the energy of our life is spent in the pursuit of pleasant feeling and that this is, at the same time, a flight from unpleasant feeling and neutral feeling. And isn't it ironic - we can never really get there.
"Whatever is felt is subject to dukkha. This I have regularly stated simply in connection with the impermanence of all compounded things (sankhara)." Samyutta XXXVI.11
Because our feelings and emotions are so dependant on supporting conditions (paccaya), and those conditions are regularly changing, the odds of arriving exactly where we want to be are slim. Even when we get close - blow me down but the price of oil goes up, weather turns bad, daughter gets pregnant, dog dies, debt collector calls.... - and it can incline to despair. But, there is hope - on two fronts.
• The first is simple. We are part of the process, we have the ability to intend, to participate in the flow of events. This is called kamma - action. But it is limited. There are many of us (god included?) intending in different directions. There is some kind of collective averaging - with right-view and goodness as the deciding factor (in the long run).
• The second is more challenging. Don't be a victim of feelings. This practice is the second foundation of mindfulness (satipatthana) and it begins by learning to understand the nature of feeling. If you can fully know the quality of pleasant feeling - just as feeling, before it evolves into perception-emotion - then you have the ability to observe the seed-point of perception-emotion. Feeling is one of those branches as you fall out of the tree - you can grab it! Just rest with the feeling. Strengthen the ability to just be with unpleasant feeling. Strengthen the ability to just be still with pleasant feeling - and not feel compelled to rush off in pursuit. This doesn't mean never doing anything but it does mean YOU HAVE A CHOICE. You no longer need be a victim, a slave to your memories, your childhood traumas, your perception fantasies and the like. It requires mindfulness and self-restraint.
"All feeling -- whether of the past, the future or the present, whether in oneself or in others, whether coarse or sublime, inferior or superior, far or near -- should be seen with right understanding as it actually is: 'This is not mine, this is not me, this is not my self.'" Samyutta XXII, 59
It is difficult to be objective about emotions, to not take them personally. Because feeling is less complex we can refine awareness of our experience to the simple level of feelings. Seeing feelings as just feelings it is easier to not get caught in the complex psychological network of perceptions and emotions that arise from those feelings. The emotions are always there, hanging around the fringes of awareness, but to see clearly: "this is pleasant feeling - pleasant feeling is like this" and to see the associated habitual movement of craving. It is pleasant - and I want it! Sometimes life is difficult, beyond our current ability to effect change. Unpleasant feeling is like this. Be at peace with that. Feeling conditions craving - but feeling not taken personally can rest, just there. It may squirm a little but it need go no further.