My boyfriend cheated on me with my sister - I can't face seeing either of them

DEAR DEIDRE: I ALWAYS felt like the ugly sister and since my boy-friend cheated on me with my little sister, I feel like the stupid one too.

I’m 28, he is 29 and my sister is 26. At Easter she came over and the evening turned into a really boozy one.

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I went to bed earlier than them, as I knew I would be up in the night with our daughter. She is three years old and is not a good sleeper.

The next morning he was a mess and my sister had gone.

I could see something was wrong with him.

He froze when I tried to cuddle him and was really withdrawn.

That evening while watching telly, I demanded to know what happened.

He said he couldn’t remember much but knew they gave each other oral sex — there on that very sofa.

He was crying and repeating how sorry he was.

He insisted it happened only because he’d been drinking heavily, not because he fancied my sister.

We’ve been together for six years.

I love him and thought I could trust him but he struggles with drink and drugs.

Bedtime fun shortlived?

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He begged me to forgive him and said it was only me he wanted to be with.

I’m not ready to forgive him, so we’re taking a break.

I’d like to sort this out and rebuild our relationship but I feel so low.

I look in the mirror and see someone fat and ugly. It makes me wonder how he could possibly want to be with me.

My sister lives just around the corner from me and I haven’t been able to face seeing her either since all this.

How can I give him another chance after cheating with my own sister?

DEIDRE SAYS: This is a very hurtful betrayal to come back from – but you can do it if you are both prepared to work hard at rebuilding the trust.

Your boyfriend will also need to address his drink and drugs misuse.

Get in touch with Al-Anon Family Groups (al-anonuk.org.uk, 0800 0086 811). They will understand what you are going through.

In addition, you and your relationship will really benefit if you can address your own feelings of low self-esteem.

Try to focus on your strengths and be kinder to yourself.

It would be so sad to break up a strong relationship over this mistake.

Couples’ counselling would help you both to put his infidelity firmly in the past.

Relate (relate.org.uk) and Tavistock Relationships (tavistockrelationships.org) both offer online counselling.