A few years ago, I got very ill and I am still suffering the after-effects. I can’t work and now struggle in social situations. I am finding myself incredibly lonely, isolated and depressed. I used to be outgoing and confident, but I have been losing contact with my old friends. I had thought it was because I often turn down invitations due to being unwell, but this week I received a message from one of my oldest friends to tell me that I bring her down and that I need to cheer up. I am heartbroken. I have so much love and friendship to offer, just not in the same way I was able to before. What should I do?

Sometimes, illnesses or injuries or bouts of depression can leave us feeling completely altered. It makes sense to me that your big life adjustment would have an effect on your social life, and I have a lot of empathy for how hard that can be.

When I had postnatal depression, I rarely saw any of my friends – it was as if they all disappeared off the face of the planet, and I was devastated. I can only assume that I was “bringing them down” and that they felt helpless to influence my mood. Sometimes people don’t realise that just sitting with us, staring at a sunset, eating soup, watching a movie – essentially just being – is all we really need. We are social creatures. In the best of friendships, you are there for each other through both celebrations and suffering.

Those outgoing and confident parts of your personality still reside somewhere inside you; they have not gone anywhere. It’s simply that other more vulnerable aspects have emerged and taken a front seat. But all these parts of you – lonely, confident, ill, outgoing – come together to make you who you are, and a true friend will recognise that.

Your friends aren’t responsible for cheering you up, but they can certainly make dark times more tolerable, even humorous. Do you have even one friend who has dived into the murky waters with you? Is there someone you have stuck with in difficult times? Sometimes even one visit from such a friend can shift the loneliness. If not, it could be time to join a support group, or try to meet new friends who want more than simply to be near you when you are in a good mood.

• Alanis Morissette’s podcast is available at iTunes and at alanis.com. Send your dilemmas about love, family or life in general to Alanis Morisette at ask.alanis@theguardian.com