How can i make the size of ellipse keeps the size after i released the mouse - processing

Question

what I need to do is:
As long as the mouse is still pressed, the shapes get smaller and smaller with each frame (already complete it)
When the mouse is released, the shapes keep their size.
When the mouse has clicked again, the „explosion“ is reset (i.e. all shapes that are still visible from the previous explosion vanish and the explosion starts again).
float gravity = .4;
int particle_each_time = 4;
ArrayList<Particle> particle= new ArrayList(); // ArrayList to manage to list of all particles
void setup() {
size(640, 480);
}
void draw() {
background(0);
for (int i = 0; i < particle_each_time; i++) {
particle.add(new Particle(mouseX, mouseY));
}
for (int i = 0; i < particle.size(); i++) {
Particle p = particle.get(i);
p.update(gravity);
p.draw();
}
}
//Next tab
class Particle {
float x; //X Position
float y; //Y Position
float velX; //velocity on X axis
float velY; //velocity on Y axis
float size; // Size of the particle
// float sizeFromMouse;
float lifespan; // duration of the particle
float col;//create fire type colours
Particle(float x, float y) {
this.velY = random(-10, 10);
this.velX = random(-10, 10);
this.x = x;
this.y = y;
this.size = 20;
lifespan = 220.0;
col = random(#DE8816);
}
void update(float gravity) {
this.x += velX; // direction of X axis
velY += gravity; // gravity affectiing the velocity on Y axis causing to fall
this.y += velY; //direction of Y axis
lifespan -= 1.0;
if (mousePressed ) {
size = size - 0.51;
}
if (size<0) {
size = 1;
}
}
boolean isDead() {
if (lifespan < 0.0) {
return true;
} else {
return false;
}
}
void draw() {
stroke(0, lifespan);
fill(#DE8816, lifespan);
ellipse(x, y, size, size);
}
}