The fact that you have stopped for several months at a time – shows that you can stop gambling. It is staying stopped which is the problem for a lot of us.
Relapsing back to gambling is part of having a gambling problem – so I am surprised that a therapist was not aware of this and was not looking out for this.
I would consider talking to your family and therapist about what you have been doing. The actual gambling is part of the problem, but so is feeling shame and thus not being able to talk about it. The more others are aware that you are in danger of relapse, the more they can help prevent that happening.
I wonder what barriers you have in place to stop going back to gambling again. Is someone else handling your finances – if not why not? Have you looked at what triggers you to gamble and then talked about this in therapy and find strategies to deal with it? Have you looked at planning your time and using it in other ways so that you are busy and less likely to respond to the urge to gamble?
You said: “Mostly because i cannt simply admit all again and because i have new debts. I am afraid that this was too much and that i will lose all now. But i can not live with this anymore.”
Neither you or I can predict how others will react to the news that you have gambled again – but the stress of keeping that secret is enough to cause you to continue and that you cannot do. You say you cannot live with this – if you are even thinking about suicide then you need to talk to someone, your family, your therapist or a helpline. Think about it – if you end your life, all that you are now keeping secret will come out – they will all know and it will be too late to help you.
Put as much effort (if not more) into your recovery as you did into your gambling. I wish you well.