Mumbai, June 25 -- Actor Karisma Kapoor is currently reeling from the sudden death of her ex-husband and industrialist Sunjay Kapur.

The businessman died after he suffered a heart attack while playing polo in London, United Kingdom on June 12, and since then Kareena Kapoor Khan and Saif Ali Khan have been making sure to be with Karisma and her children Samaira and Kiaan.

As it's Karisma's birthday on Wednesday, Kareena penned an uplifting note for "Lolo", giving her strength.

"This is my most favourite picture of you both. To the strongest and the bestest girl in the universe... It's been a tough year for us ...but you know what ...as they say tough times don't last ...the toughest sisters do...To my Sister ,my mother ,my best friend ....