The opposite of being reactive is being response-able, i.e. responsible. When you are being responsible, you're thinking as well as feeling: you're experiencing your feelings but also conscious of your Self and therefore not driven by emotion to act impulsively. As you become free from reactive (stimulus-response) behavior then to that degree you know that you are also free to be spontaneous, because you know that will incorporate responsibility.
Responsibility also allows you to maintain your self-worth, despite anything your parents, or anybody else for that matter, might say about you. The thoughts and feelings of others no longer drag you into a pit of self-doubt. You will see all sorts of new options and choices in your dealings with other people because your perspective and your sense of reason are not being buried by emotions. Taking responsibility for your mind, puts back into your hands a good deal of control over your life.
By understanding how easily reactive responses can take over one's behavior you will find yourself not taking personal offense when others behave badly; you can see that they are just dramatizing the problems and conflicts in their own heads. Enlightenment always leads to understanding, empathy and improved communication, in short, love.
Reframing is to make statements of responsibility that empower your choice in a situation, rather than being at effect or a victim.
When parents and others continue to attempt to manipulate and dominate, you can then stay calm and refuse to be stampeded: then you retain the power. For example by responding non-defensively, this breaks the cycle of attack-retreat-defense-escalation. The moment you argue, apologise, explain, or try to get them to change their minds, you give them the power to withhold the understanding that you are asking them for. One can say, 'That's an interesting point of view', or 'I shall consider that as one option'. It is also necessary to assert one's position in a matter-of-fact manner, without worrying about upsetting them, but without any hostility or embarrassment: 'I'm happy to let you stay for a specified, limited time'.
One's response to this approach may be to say 'I just don't think I can stand up to my parents'. Instead of saying 'I can't', reframe your statement in the form: 'I haven't yet stood up to my parents'. 'Haven't yet' implies choice, whereas 'don't' and 'can't' imply the opposite: finality. Similarly, 'I mustn't' or 'I shouldn't' can be reframed as : 'I could choose not to'. 'I should' or 'I must' can be reframed: 'I could choose to'. There is a big difference between choosing to capitulate to your parents because you've considered the alternatives and decided that you're not prepared to make a change at this moment, and automatically capitulating because you feel helpless. Making a choice means taking a step towards control; knee-jerk reacting means backsliding into being controlled.
These same principles of course apply to all relationships, not just child-parent ones.